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Physics

Chapter 3 Technical Measurements and Vectors
3.1

When we look at objects in terms of length, weight, speed, time, force, and mass, we are looking at the object's physical qualities, how tall it is, how fast its going, etc. An example would be the weight of a brick, the weight of a brick 2 lbs. What was just said about the brick was the object's Magnitude. Magnitude of a physical quantity is determined by number and unit of measure. So, if we say a building is 30 feet tall, the buildings magnitude would be 30 feet. Another important note is the use of Standards, these are permanent or easily determined physical unit of the size of a physical unit. An example would be a foot, we all know that a standard foot is 12 inches long.

3.2

The international system of units is also known as SI, or what we know as the metric system. This system was developed with the idea of having a globally set standard of units of measure. However in the United States we have yet to join the rest of the world and so we still use the U.S Customary system of Units or USCS.

3.3

The SI unit, meter (m) was originally defined as one ten-millionth of the distance from the North Pole to the Equator.

3.4

If we were measuring something and it came out to be, 3.42cm. the last digit is estimated and therefore is susceptible to error. the actual measurement would fall between 3.40 and 3.50 cm. to write the measurement as 3.420cm would imply greater accuracy than was justified. We say that the number has three significant figures, and we are careful not to write more numbers or zeros than are meaningful. Sll physical measurements are assumed to be approximate, with the last significant digit having been determined by an estimation. 4.003 has 4 significant figures, 0.34 has 2 signifcant figures. A significant figure is known as a reliably known digit. There exists two rules, 1; when approximate numbers are multiplied or divided, the number of significant digits in the reported result is the same as the number of significant digits in the least accurate of the factors. By "least accurate" we mean the factor lowest number of significant digits. Rule 2; when approx. numbers are added or subtracted, the number of decimal places in the result should equal the smallest number of decimal places of any term in the sum. Basically what this is saying is that don't write down more numbers than are needed, because someone else looking at them may think they have to be that specific, when they don't have to be.

3.5

Whatever device we choose to take measurements with is directly determined by the physical conditions surrounding the measuring instrument. So to measure temperature we use a thermometer, due to the fact that it is either hot or cold where we are.

3.6

We know that the length of 1 inch is eaqual to the length of 25.4 milimeters. We would write this as a 25.4mm/1in, this ratio is known as a conversion factor. Sometimes we have to use multiple units in certain quantities. Speed for example, uses both length and time, for exampl meters per second. If 2 quantities are to be added or subtracted they must be the same dimensions, if the quantities on both sides of an equals sign must be of the same dimensions.

3.7

Quantities that are expressed solely by number are Scalar Quantities, such as 50 km, 40ft^3. Scalar Quantities are expressed only by their magnitudes- number and unit. When quantities have a direction added to their magnitude, they become vector quantities, as in 40Km/h 30 degrees N.

3.8

The polygon method is the more useful one, since it can be readily applied to more than two vectors. The parallelogram method is useful for the addition of two vectors at a time.

3.9

The most familiar force is weight, which is the gravity exerted on every body on the Earth. Here in the U.S weight is measured in pounds (lbs) as where in SI weight is measured in Newtons (N). As a vector quantity weight is directed towards the center of the Earth. 1 N=.225lbs and 1lb = 4.45N. There are two measureable effects of forces, changing the dimensions or shape of a body, and changing a body's motion. The 1st case, if there's no resultant displacement of the body, the push or pull causing the change in shape is called Static Force. If a force changes the motion of a body it is called a dynamic force.

3.10

When 2 or more forces act at the same point on an object, they are said to be concurrent forces. The combined effect of such forces is called the resultant force. If we had two concurrent forces moving in the same direction, then the resultant force would be the sum of those two forces. For exmaple if we applied 5N of force to an object and then added another 35N of force in the same direction and location then our resultant force would be 40N of net force (total force).

3.11

To find the resultant vector or the components of a vector, we use Right-triangle trigonometery, or Pythagorean Theorem.

3.12

Due to Trig. we will use that to make sure our final results are accurate, the only estimating that need be done, is with the vectors themselves. For example a 60 N force should be drawn as a vector three times as long as the vector for a 20 N force. The given angles should also be estimated.

Chapter 4 Translational Equilibrium and Friction
4.1

Equilibrium = Balance Friction a horizontal action in which an object sliding across another which generates heat, and causes said object to slow down. Without friction a ball rolling across the floor would never come to a stop. Newton's First law of Motion: A body at rest will remain at rest, a body in motion will remain in motion in a straight line unless acted on by an external force. This law is expressed under ideal conditions, due to friction an object motion will, given time, come to a stop. Another name for this law is the law of inertia, Inertia, is the property of a particle that allows it to maintain a constant state of motion or rest. This law states that if you are sitting still, you will remain seated, unless something comes along and moves you out of the chair. The same can be said for moving objects, if you move in a straight line, you will keep moving in that straight line unless something hits you and moves you out of line.

4.2

If an object remains in a constant state of motion, it requires a resultant force (f) of some amount to generate it's acceleration (a). In other words the amount of force applied to an object will generate movement. However, an object's mass (m) decreases give the amount of mass an object has. For instance if you push a small box across a table a certain amount of force will be required to cause movement. That being said if you had a larger box, you would have to exert more force on the box in order to generate movement. Newton's Second Law of Motion: The acceleration (a) of an object in the direction of a resultant force (f) is directly proportional to the magnitude of the force and inversely proportional to the mass (m). A simple equation represents this Law. Basically, this law states that, the amount of force an object has, is determined by how big it is and how fast it moves. So say if you punched a punching bag, the force of your punch will be determined by, the size (mass) of your fist, multiplied by how fast you throw the punch (acceleration). Force= (Mass)(Acceleration)  F= ma
 * Note that when velocity does not change acceleration is zero. There is also no resultant force on objects at rest and moving at constant speed (a= 0). Lets say you punch a bag, the force you punch the bag with is based on how fast your fist moves, and how big your fist is.

4.3

There can be no force if two or more bodies are not involved, an object cannot begin moving simply of it's own volition. When a boxer punches a bag, his fist exerts an "action" force on the bag. However, the bag also exerts a "reaction" force back at the fist. When two objects interact the force exerted by the second body on the first (Reaction force) is equal in magnitude and opposite in direction to the force exerted by the first on the second (action force). Newton's Third Law of Motion: For every action, there must be an equal and opposite reaction. What this law means, is that if you push against the wall, the wall will push back with the same amount of force.

4.4

Equilibrium exists when all external forces register as zero, meaning there is no unbalanced force causing acceleration. Therefore in Newton's 1st Law an object in equilibrium must either be at rest or be moving at constant velocity. The term Transitional Equilibrium is used to distinguish the first condition from the second condition for equilibrium, which involves rotational motion, (see Chapter 5).

4.6

see book

4.7

When a body moves while in contact with the surface of another object, friction forces oppose the relative motion. Friction is caused by the adhesion of one surface to the other and by the interlocking or irregularities in the rubbing surfaces. It is this friction that allows us to walk, brakes on a vehicle to work, etc. Friction generates heat, which can cause damage. When the space shuttle reenters the Earth's atmosphere, the friction generated between the heat shield of the shuttle and the atmosphere creates incredibly high heat, which (if the heat shield doesn't hold) will destroy the shuttle. Static friction, occurs when an object is being forced to move but the friction holds it in place. Kinetic friction, occurs when an object is moving and the friction is creating drag on the object.

Chapter 6 Uniform Acceleration
6.1

The simplest kind of motion in an object is uniform motion in a straight line. If an object covers the same distance in each successive unit of time, it is said to move with constant speed. Whether speed is constant or not, the average speed is defined by; Average speed= distance traveled/ time elapsed. Sometimes objects cannot always travel at constant velocity, certain adverse conditions may arise that cause said object to either slow down or speed up. So, we use what is called instantaneous speed. Supposed we used a line with it's start marked A, and B being the finish point or destination of the object. We would use an arbitrary point C to represent the moment of instantaneous speed. Basically point C is the recording we use to see what speed an object was moving at a given time.

6.2

If an object is not moving at a constant speed but, speeding up, we say it's accelerating. Acceleration is calculated as Acceleration = change in time/ time interval.

6.3

The simplest kind of acceleration is motion in a straight line in which the speed changes at a constant rate. This kind of special motion is called uniform acceleration or constant acceleration. When speed is reduced we call deceleration, but this term is problematic due to the fact that acceleration a =-1.39m/s^2, which really means that velocity becomes more negative by said amount every second. So the term deceleration is incorrect, acceleration means a change in velocity, which can mean either an increase or a decrease in speed.

6.4 & 6.5 See book for mathematics and graph details.

6.6

Generally we consider upward motion to be positive and downward motion to be negative. If a child were to throw a baseball in the air at a rate of 2m/s^2 it would accelerate in a positive direction, until eventually it stopped and begins moving in a negative direction eventually reaching the same speed with which it was thrown. Once an object is thrown in a positive direction, the following conventions will determine the signs of velocity, displacement, and acceleration. Displacement is positive or negative depending on the location or coordinate of position of the object relative to its zero position. Velocity is positive or negative depending on whether the direction of motion is with or against the chosen positive direction. Acceleration is positive or negative depending on whether the resultant force is with or against the positive direction.

6.7

Much of what we know today about falling objects came from Galileo Galilee. He was the first to deduce that in the absence of friction all bodies, large or small, heavy or light, fall to Earth with the same acceleration. Assuming we eliminated air friction, all falling bodies accelerate under the term gravitational acceleration. At sea level and at 45 degrees latitude this acceleration has been measure to be 9.806 m/s^2 and is denoted by g. This form of acceleration is a constant one. Meaning that if you drop something, it will always fall with same acceleration.

6.8

If an object is launched without being under its own power, we call it a projectile. When a ball is thrown, is an example of a projectile.

6.9

If a projectile is fired horizontally, its motion can best be described by considering its horizontal and vertical motion separately. For instance, it a ball was projected horizontally, while at the same time another ball was dropped vertically. they would both land at the same time.

Chapter 7 Newton's Second Law
7.1

A machine using a straight rail, covered with air holes, where air is force through the rail, thus allowing anything that rides on the rail, to actually ride on a cushion of air. A device such as this one, would be used to measure how force acts on a object of a given mass, without worrying about friction. The equation for Newton's second Law is Resultant force= mass x acceleration. Using a friction-less device such as this helps us, because friction will slow down the acceleration.

7.2

Before we can use newton's second law, we must be able to decern the difference between weight and mass. Generally we see the unit of force, its often used as a mass unit. The Kilogram is a unit of mass, it is often used in industry as a unit of force. Mass is a universal constant equal to the ratio of a body's weight to the gravitational acceleration due to its weight. Weight is the force of gravitational attraction and varies depending on the acceleration of gravity.

7.3

According to Newton's Second law, a resultant force always produces an acceleration in the direction of the resultant force. So if you push a box forward, it will slide forward.

Chapter 8 Work, Energy and power
8.1

The capacity for doing work is called energy, and the rate at which accomplished is defined as power. When the space shuttle takes off, it requires a huge amount of force, to achieve lift off. Now, the fuel stored in the solid fuel booster rockets that the shuttle is attached to, is the energy portion. The rate at which the shuttle takes off is the power. So, the fact that shuttle ascended from the ground and reached orbit is called work. For work to be done three things need to happen...

1. There must be an applied force

2. The force must act through a certain distance, called the displacement.

3. The force must have a component along the displacement.

Work is a scalar quantity equal to the magnitudes of the displacement and the component of the force in the direction of the displacement. Joule, a SI unit that is the unit of measure for power.

8.2

The term resultant work (total work) comes from the multiple forces that effect an object.

8.3

There are several forms of energy in mechanics there are two major forms. Kinetic Energy K: energy possessed by a body by virtue of its motion. Potential Energy U: energy possessed by a system by virtue of position or condition. So lets say we have a gun, the powder store in the bullet is the potential energy. Once the bullet is fired the, it impacts a target. The energy or force it hit the target with is the bullet's kinetic energy.

8.4

The resultant work done on a mass by a constant force acting through a distance is equal to its change in kinetic energy. This is what we call work-energy theorem. We can use this theorem to find the average force of an object.

8.5

If we had a crane and hold a 2,000 lb object 50 feet in the air, it has potential energy, due to the body-Earth system. The gravitational potential energy for an air plane is significantly different than a moutain, sky scraper, or the ocean. The energy is unchanging,the energy in the stone used in the building of the Pyramids of Giza in Egypt which were built 2500 years ago, still have the same potential energy.

8.6

Conservation of mechanical energy: in the absence of air resistance or other dissipative forces, the sum of the potential and kinetic energies is a constant, provided that no energy is added to the system.

8.7

Lets say a car is moving down the road with 1000 j of force, it loses 400j due to friction, so it has 600j left for the velocity of the car. Initial total energy = final total energy + losses due to friction.

Conservation of Energy: The total energy of a system is always constant, although energy changes from one form to another may occur within the system.

8.8

In the definition of work, time is not involved in any way. But when calculating power it is. Power = work/time The SI unit for power is the joule per second, which was renamed the watt.

Chapter 16 Temperature and Expansion
16.1

Thermal energy represents the total internal energy of an object: the sum of its molecular kinetic and potential energies. When a meteorite impacts the Earth, it is super heated by falling through the atmosphere. After impact, it eventually cools and becomes stable. We call this Thermal Equilibrium. Seeing as classical mechanics alone cannot accurately describe the changes in thermal energy, we must use a different property to determine if they will be at thermal equilibrium with other objects, we call this property Temperature.

16.2

A device known as a thermometer is used to measure temperature. Two temps that can be reproduced easily are, lower fixed point and upper fixed point. The lower fixed point (ice point) is the temp at which water and ice coexist in thermal equilibrium under a pressure of 1 atm. The upper fixed point (steam point) is the temp at which water and steam coexist n equilibrium under a pressure of 1 atm. The Celsius scale arbitrarily assigned the number 0 to the ice point and the number 100 to the steam point. Each division or unit on the scale is called a degree (°). For example, room temperature is often taken as 20°C, which is read as twenty degrees Celsius. The development of this scale was based on the choice of different fixed points. Fahrenheit chose the temperature of a freezing solution of salt water as his lower fixed point and assigned it the number and unit of 0°F. Relating the Fahrenheit scale to the universally accepted fixed points on the Celsius scale, it can be shown that 0 and 100°C correspond to 32 and 212°F.The reason for these different ways to measure the temperature, is that certain temperatures, are so high or low, that it was easier to use these units, that and they made for greater accuracy.

16.3

While mercury is common to the thermometer, it is not as accurate, the most accurate are gas thermometers, where the gas expands in the same way when heated. There are two kinds of gas thermometers. One kind maintains a constant pressure and utilizes the increases in volume as an indicator. This type is called a constant-pressure thermometer. The other kind, called a constant-volume thermometer, measures the increase in pressure as a function of temperature.

16.4

Both Celsius and Fahrenheit have limitations, neither of these have a true 0 degree temp. Absolute Zero is the point where all thermal energy stops, it is measured as -273.15 degrees C or -460 degrees F. An absolute temperature scale has as its zero point the absolute zero of temperature. One such scale was devised by Lord Kelvin (1824–1907). The standard interval on this scale, the kelvin, has been adopted by the international (SI) metric system as the base unit for temperature measurement. The interval on the Kelvin scale represents the same change in temperature as the Celsius degree. Thus, an interval of 5 K (reads “five kelvins”) is exactly the same as 5 C°.

16.5 A change in any one dimension of a solid is called linear expansion.

16.6

Linear expansion is by no means restricted to the length of a solid. Any line drawn through the solid will increase in length per unit length at the rate given by its expansion coefficient α. For example, in a solid cylinder, the length, diameter, and a diagonal drawn through the solid will all increase their dimensions in the same proportion. So, if one thing gets bigger in a solid object, the rest grow as well.

16.7

The symbol β (beta) is the volume expansion coefficient. It represents the change in volume per unit volume per degree change in temperature. For solid materials, it is approximately three times the linear expansion coefficient.

16.8

Say we fill the bulb of the tube in with water at 0°C so that the narrow neck is partially filled. Expansion or contraction of the water can be measured easily by observing the water level in the narrow tube. As the temperature of the water increases, the water in the tube will gradually sink, indicating a contraction. Basically, heat makes things get bigger, while the cold makes them get smaller.

Chapter 17 Quantity of Heat
17.1

It was originally believed that two systems reach thermal equilibrium through the transfer of a substance called caloric. The equivalence of heat and work as two forms of energy was established later by Sir James Prescott Joule.

17.2

The idea of heat as a substance must be discarded. It is not something that an object has but something that it gives up or absorbs. Heat is simply another form of energy that can be measured only in terms of the effect it produces. The SI unit of energy, the joule, is also the preferred unit for heat since heat is a form of energy. There are three older units that remain in use today, however, and they will also be treated in this text. These earlier units were based on the thermal energy required to produce a standard change. They are the calorie, the kilo-calorie, and the British thermal unit. One calorie (cal) is the quantity of heat required to change the temperature of 1 gram of water through 1 Celsius degree. Heat has energy, in the beginning people tied to give this energy a unit of measure. the early attempts didn't work, until the joule came along.

17.3

The heat capacity of a body is the ratio of heat supplied to the corresponding rise in temperature of the body. Basically what this is saying is that all objects take different amounts of time to heat up.

17.4

The term heat has now been introduced as the thermal energy absorbed or released during a temperature change. The quantitative relationship between heat and temperature is best described by the concept of specific heat. The physical relationships among all these terms are now beginning to fall into place. The principle of thermal equilibrium tells us that whenever objects are placed together in an insulated enclosure, they will eventually reach the same temperature. This is the result of a transfer of thermal energy from the warmer bodies to the cooler bodies. If energy is to be conserved, we say that the heat lost by the warm bodies must equal the heat gained by the cool bodies. Basically Heat loss=heat gain. Say you grab an ice cube, and it starts to melt, the heat from your body that is lost to the ice cube, is the same amount gained by the ice cube.

Chapter 18 Transfer of Heat
18.1

Conduction: by molecular collisions between neighboring molecules. For example, if we hold one end of an iron rod in a fire, the heat will eventually reach our hand through the process of conduction. The increased molecular activity at the heated end is passed on from molecule to molecule until it reaches the hand. The process will continue as long as there is a difference in temperature along the rod. Conduction is the process in which heat energy is transferred by adjacent molecular collisions throughout a material medium. The medium itself does not move. Convection is the process by which heat is transferred by the actual mass motion of a fluid. Heat moves from hot to cold, so when you grab a pot on the stove, it might not be warm, but if you grab it after the water in the pot has started to boil, it might burn you.

18.2

From the defining equation, one can see that substances with a large thermal conductivity are good conductors of heat, whereas substances of low conductivity are poor conductors, or insulators. The thermal conductivity of a substance is a measure of its ability to conduct heat and is defined by the relation.

18.3

Convection has been defined as the process in which heat is transferred by the actual mass motion of a material medium. A current of liquid or gas that absorbs energy at one place and then moves to another place, where it releases heat to a cooler portion of the fluid, is called a convection current. If the motion of a fluid is caused by a difference in density that accompanies a change in temperature, the current produced is referred to as natural convection. The water flowing through the glass tubing in the previous example represents a natural-convection current. When a fluid is called to move by the action of a pump or fan, the current produced is referred to as forced convection.

Chapter 19 Thermal Properties of Matter
19.1

One of the most useful generalizations about gases is the concept of an ideal gas, whose behavior is completely unaffected by cohesive forces or molecular volumes. Of course, no real gas is ideal, but under ordinary conditions of temperature and pressure, the behavior of any gas conforms closely to the behavior of an ideal gas. Therefore, experimental observations of many real gases can lead to the derivation of general physical laws governing their thermal behavior. Charles's Law: Provided that the mass and pressure of a gas are held constant, the volume of the gas is directly proportional to its absolute temperature. Basically, the amount of gas in a certain space is determined by how hot or cold it is.

19.2

Gay-Lussac's Law: If the volume of a sample of gas remains constant, the absolute pressure of the gas is directly proportional to its absolute temperature. If you take a small amount of gas, and its amount remains constant, due to temperature.

19.3

Let us now consider the effect of a change in mass on the behavior of gases. If the temperature and volume of an enclosed gas are held constant, the addition of more gas will result in a proportional increase in pressure. Similarly, if the pressure and temperature are fixed, an increase in the mass will result in a proportional increase in the volume.

19.4

Although the mass of individual atoms is difficult to determine because of their size, experimental methods have been successful in measuring atomic mass. When working with macroscopic quantities, such as volume, pressure, and temperature, it is much more convenient to compare the relative masses of individual atoms.

Chapter 3 Technical Measurements and Vectors
3.1

The language of physics and technology is a universal one. If we were working on an engine and we knew that this engine had a piston which displaces 3.28 liters. We would first ask ourselves two questions, what is piston displacement and what is a liter? Piston displacement is the volume the piston displaces as it moves up and down, and a liter is an easily recognizable unit of measure. Thus all mechanics would use this term and system, due to it being universal. When we look at objects in terms of length, weight, speed, time, force, and mass, we are looking at the object's physical qualities. An example would be the weight of a bar bell, the weight of a bar bell is 45 lbs. Whats was just said about the bar bell was the object's Magnitude. Magnitude of a physical quantity is determined by number and unit of measure. Another important note is the use of Standards, these are permanent or easily determined physical unit of the size of a physical unit. An example would be a foot, we all know that a standard foot is 12 inches long.

3.2

The international system of units is also known as SI, or what we know as the metric system. This system was developed with the idea of having a globally set standard of units of measure. However in the United States we have yet to join the rest of the world and so we still use the U.S Customary system of Units or USCS.

3.3

The SI unit, meter (m) was originally defined as one ten-millionth of the distance from the North Pole to the Equator.

3.4

If we were measuring something and it came out to be, 3.42cm. the last digit is estimated and therefore is susceptible to error. the actual measurement would fall between 3.40 and 3.50 cm. to write the measurement as 3.420cm would imply greater accuracy than was justified. We say that the number has three significant figures, and we are careful not to write more numbers or zeros than are meaningful. All physical measurements are assumed to be approximate, with the last significant digit having been determined by an estimation. 4.003 has 4 significant figures, 0.34 has 2 significant figures. A significant figure is known as a reliably known digit. There exists two rules, 1; when approximate numbers are multiplied or divided, the number of significant digits in the reported result is the same as the number of significant digits in the least accurate of the factors. By "least accurate" we mean the factor lowest number of significant digits. Rule 2; when approx. numbers are added or subtracted, the number of decimal places in the result should equal the smallest number of decimal places of any term in the sum.

3.5

Whatever device we choose to take measurements with is directly determined by the physical conditions surrounding the measuring instrument.

3.6

We know that the length of 1 inch is equal to the length of 25.4 millimeters. We would write this as a 25.4mm/1in, this ratio is known as a conversion factor. Sometimes we have to use multiple units in certain quantities. Speed for example, uses both length and time, for example meters per second. If 2 quantities are to be added or subtracted they must be the same dimensions, if the quantities on both sides of an equals sign must be of the same dimensions.

3.7

Quantities that are expressed solely by number are Scalar Quantities, such as 50 km, 40ft^3. Scalar Quantities are expressed only by their magnitudes- number and unit. When quantities have a direction added to their magnitude, they become vector quantities, as in 40Km/h 30 degrees N.

3.8

The polygon method is the more useful one, since it can be readily applied to more than two vectors. The parallelogram method is useful for the addition of two vectors at a time.

3.9

The most familiar force is weight, which is the gravity exerted on every body on the Earth. Here in the U.S weight is measured in pounds (lbs) as where in SI weight is measured in Newtons (N). As a vector quantity weight is directed towards the center of the Earth. 1 N=.225lbs and 1lb = 4.45N. There are two measurable effects of forces, changing the dimensions or shape of a body, and changing a body's motion. The 1st case, if there's no resultant displacement of the body, the push or pull causing the change in shape is called Static Force. If a force changes the motion of a body it is called a dynamic force.

3.10

When 2 or more forces act at the same point on an object, they are said to be concurrent forces. The combined effect of such forces is called the resultant force. If we had two concurrent forces moving in the same direction, then the resultant force would be the sum of those two forces. For example if we applied 5N of force to an object and then added another 35N of force in the same direction and location then our resultant force would be 40N of net force (total force).

3.11

To find the resultant vector or the components of a vector, we use Right-triangle trigonometry, or Pythagorean Theorem.

3.12

Due to Trig. we will use that to make sure our final results are accurate, the only estimating that need be done, is with the vectors themselves. For example a 60 N force should be drawn as a vector three times as long as the vector for a 20 N force. The given angles should also be estimated.

Chapter 4 Translational Equilibrium and Friction
4.1

Equilibrium = Balance Friction a horizontal action in which an object sliding across another which generates heat, and causes said object to slow down. Without friction a ball rolling across the floor would never come to a stop. Newton's First law of Motion: A body at rest will remain at rest, a body in motion will remain in motion in a straight line unless acted on by an external force. This law is expressed under ideal conditions, due to friction an object ain motion will, given time, come to a stop. Another name for this law is the law of inertia, Inertia, is the property of a particle that allows it to maintain a constant state of motion or rest.

4.2

If an object remains in a constant state of motion, it requires a resultant force (f) of some amount to generate it's acceleration (a). In other words the amount of force applied to an object will generate movement. However, an object's mass (m) decreases give the amount of mass an object has. For instance if you push a small box across a table a certain amount of force will be required to cause movement. That being said if you had a larger box, you would have to exert more force on the box in order to generate movement. Newton's Second Law of Motion: The acceleration (a) of an object in the direction of a resultant force (f) is directly proportional to the magnitude of the force and inversely proportional to the mass (m). A simple equation represents this Law. Force= (Mass)(Acceleration)  F= ma
 * Note that when velocity does not change acceleration is zero. There is also no resultant force on objects at rest and moving at constant speed (a= 0).

4.3

There can be no force if two or more bodies are not involved, an object cannot begin moving simply of it's own volition. When a boxer punches a bag, his fist exerts an "action" force on the bag. However, the bag also exerts a "reaction" force back at the fist. When two objects interact the force exerted by the second body on the first (Reaction force) is equal in magnitude and opposite in direction to the force exerted by the first on the second (action force). Newton's Third Law of Motion: For every action, there must be an equal and opposite reaction.

4.4

Equilibrium exists when all external forces register as zero, meaning there is no unbalanced force causing acceleration. Therefore in Newton's 1st Law an object in equilibrium must either be at rest or be moving at constant velocity. The term Transitional Equilibrium is used to distinguish the first condition from the second condition for equilibrium, which involves rotational motion, (see Chapter 5).

4.6

see book

4.7

When a body moves while in contact with the surface of another object, friction forces oppose the relative motion. Friction is caused by the adhesion of one surface to the other and by the interlocking or irregularities in the rubbing surfaces. It is this friction that allows us to walk, brakes on a vehicle to work, etc. Friction generates heat, which can cause damage. When the space shuttle reenters the Earth's atmosphere, the friction generated between the heat shield of the shuttle and the atmosphere creates incredibly high heat, which (if the heat shield doesn't hold) will destroy the shuttle. Static friction, occurs when an object is being forced to move but the friction holds it in place. Kinetic friction, occurs when an object is moving and the friction is creating drag on the object.

Chapter 6 Uniform Acceleration
6.1

The simplest kind of motion in an object is uniform motion in a straight line. If an object covers the same distance in each successive unit of time, it is said to move with constant speed. Whether speed is constant or not, the average speed is defined by; Average speed= distance traveled/ time elapsed. Sometimes objects cannot always travel at constant velocity, certain adverse conditions may arise that cause said object to either slow down or speed up. So, we use what is called instantaneous speed. Supposed we used a line with it's start marked A, and B being the finish point or destination of the object. We would use an arbitrary point C to represent the moment of instantaneous speed.

6.2

If an object is not moving at a constant speed but, speeding up, we say it's accelerating. Acceleration is calculated as Acceleration = change in time/ time interval.

6.3

The simplest kind of acceleration is motion in a straight line in which the speed changes at a constant rate. This kind of special motion is called uniform acceleration or constant acceleration. When speed is reduced we call deceleration, but this term is problematic due to the fact that acceleration a =-1.39m/s^2, which really means that velocity becomes more negative by said amount every second. So the term deceleration is incorrect, acceleration means a change in velocity, which can mean either an increase or a decrease in speed.

6.4 & 6.5 See book for mathematics and graph details.

6.6

Generally we consider upward motion to be positive and downward motion to be negative. If a child were to throw a baseball in the air at a rate of 2m/s^2 it would accelerate in a positive direction, until eventually it stopped and begins moving in a negative direction eventually reaching the same speed with which it was thrown. Once an object is thrown in a positive direction, the following conventions will determine the signs of velocity, displacement, and acceleration. Displacement is positive or negative depending on the location or coordinate of position of the object relative to its zero position. Velocity is positive or negative depending on whether the direction of motion is with or against the chosen positive direction. Acceleration is positive or negative depending on whether the resultant force is with or against the positive direction.

6.7

Much of what we know today about falling objects came from Galileo Galilee. He was the first to deduce that in the absence of friction all bodies, large or small, heavy or light, fall to Earth with the same acceleration. Assuming we eliminated air friction, all falling bodies accelerate under the term gravitational acceleration. At sea level and at 45 degrees latitude this acceleration has been measure to be 9.806 m/s^2 and is denoted by g. This form of acceleration is a constant one.

6.8

If an object is launched without being under its own power, we call it a projectile.

6.9

If a projectile is fired horizontally, its motion can best be described by considering its horizontal and vertical motion separately. For instance, it a ball was projected horizontally, while at the same time another ball was dropped vertically. they would both land at the same time.

Chapter 7 Newton's Second Law
7.1

A machine using a straight rail, covered with air holes, where air is force through the rail, thus allowing anything that rides on the rail, to actually ride on a cushion of air. A device such as this one, would be used to measure how force acts on a object of a given mass, without worrying about friction. The equation for Newton's second Law is Resultant force= mass x acceleration. 1lb=4.448 N 1 slug= 14.59 kg.

7.2

Before we can use newton's second law, we must be able to decern the difference between weight and mass. Generally we see the unit of force, its often used as a mass unit. The Kilogram is a unit of mass, it is often used in industry as a unit of force. Mass is a universal constant equal to the ratio of a body's weight to the gravitational acceleration due to its weight. Weight is the force of gravitational attraction and varies depending on the acceleration of gravity.

7.3

According to Newton's Second law, a resultant force always produces an acceleration in the direction of the resultant force.

7.4

When solving a problem involving the 2nd law of motion, use the following.

1. Read the problem carefully and then draw and label a rough sketch

2. Indicate all give information and statae what is to be found

3. Construct a free-body diagram for each object undergoing acceleration and choose an x or y axis along the continuous line of motion

4. Indicate a consistent choice for the positive direction along the continuous line of motion

5. Be careful not to confuse the weight of an object with its mass: W = mg  m = W/g

6. From the free-body diagram(s), determine the resultant force along the assumed positive line of motion

7. Determine the total mass of the system

8. Set resultant force equal to the total mass times the acceleration a.

9. Substitute all given quantities and solve for the unknown.

Chapter 8 Work, Energy and power
8.1

The capacity for doing work is called energy, and the rate at which accomplished is defined as power. When the space shuttle takes off, it requires a huge amount of force, to achieve lift off. Now, the fuel stored in the solid fuel booster rockets that the shuttle is attached to, is the energy portion. The rate at which the shuttle takes off is the power. So, the fact that shuttle ascended from the ground and reached orbit is called work. For work to be done three things need to happen...

1. There must be an applied force

2. The force must act through a certain distance, called the displacement.

3. The force must have a component along the displacement.

Work is a scalar quantity equal to the magnitudes of the displacement and the component of the force in the direction of the displacement. Joule, a SI unit that is the unit of measure for power.

8.2

The term resultant work (total work) comes from the multiple forces that effect an object.

8.3

There are several forms of energy in mechanics there are two major forms. Kinetic Energy K: energy possessed by a body by virtue of its motion. Potential Energy U: energy possessed by a system by virtue of position or condition. So lets say we have a gun, the powder store in the bullet is the potential energy. Once the bullet is fired the, it impacts a target. The energy or force it hit the target with is the bullet's kinetic energy.

8.4

The resultant work done on a mass by a constant force acting through a distance is equal to its change in kinetic energy. This is what we call work-energy theorem. We can use this theorem to find the average force of an object.

8.5

If we had a crane and hold a 2,000 lb object 50 feet in the air, it has potential energy, due to the body-Earth system. The gravitational potential energy for an air plane is significantly different than a mountain, sky scraper, or the ocean. The energy is unchanging,the energy in the stone used in the building of the Pyramids of Giza in Egypt which were built 2500 years ago, still have the same potential energy.

8.6

Conservation of mechanical energy: in the absence of air resistance or other dissipative forces, the sum of the potential and kinetic energies is a constant, provided that no energy is added to the system.

8.7

Lets say a car is moving down the road with 1000 j of force, it loses 400j due to friction, so it has 600j left for the velocity of the car. Initial total energy = final total energy + losses due to friction.

Conservation of Energy: The total energy of a system is always constant, although energy changes from one form to another may occur within the system.

8.8

In the definition of work, time is not involved in any way. But when calculating power it is. Power = work/time The SI unit for power is the joule per second, which was renamed the watt.

Chapter 16 Temperature and Expansion
16.1

Thermal energy represents the total internal energy of an object: the sum of its molecular kinetic and potential energies. When a meteorite impacts the Earth, it is super heated by falling through the atmosphere. After impact, it eventually cools and becomes stable. We call this Thermal Equilibrium. Seeing as classical mechanics alone cannot accurately describe the changes in thermal energy, we must use a different property to determine if they will be at thermal equilibrium with other objects, we call this property Temperature.

16.2

A device known as a thermometer is used to measure temperature. Two temps that can be reproduced easily are, lower fixed point and upper fixed point. The lower fixed point (ice point) is the temp at which water and ice coexist in thermal equilibrium under a pressure of 1atm. The upper fixed point (steam point) is the temp at which water and steam coexist n equilibrium under a pressure of 1 atm. The Celsius scale arbitrarily assigned the number 0 to the ice point and the number 100 to the steam point. Each division or unit on the scale is called a degree (°). For example, room temperature is often taken as 20°C, which is read as twenty degrees Celsius. Another scale for measuring temperature was developed in 1714 by Gabriel Daniel Fahrenheit. The development of this scale was based on the choice of different fixed points. Fahrenheit chose the temperature of a freezing solution of salt water as his lower fixed point and assigned it the number and unit of 0°F. Relating the Fahrenheit scale to the universally accepted fixed points on the Celsius scale, it can be shown that 0 and 100°C correspond to 32 and 212°F.

16.3

While mercury is common to the thermometer, it is not as accurate, the most accurate are gas thermometers, where the gas expands in the same way when heated. There are two kinds of gas thermometers. One kind maintains a constant pressure and utilizes the increases in volume as an indicator. This type is called a constant-pressure thermometer. The other kind, called a constant-volume thermometer, measures the increase in pressure as a function of temperature.

16.4

Both Celsius and Fahrenheit have limitations, neither of these have a true 0 degree temp. Absolute Zero is the point where all thermal energy stops, it is measured as -273.15 degrees C or -460 degrees F. An absolute temperature scale has as its zero point the absolute zero of temperature. One such scale was devised by Lord Kelvin (1824–1907). The standard interval on this scale, the kelvin, has been adopted by the international (SI) metric system as the base unit for temperature measurement. The interval on the Kelvin scale represents the same change in temperature as the Celsius degree. Thus, an interval of 5 K (reads “five kelvins”) is exactly the same as 5 C°. The triple point of water, which is the single temperature and pressure at which water, water vapor, and ice can coexist in thermal equilibrium. To remain consistent with earlier measurements, the temperature for the triple point of water was set at exactly 273.16 K. The kelvin is now defined as the fraction 1/273.16 of the temperature of the triple point of water. A second absolute scale, called the Rankine scale, remains in very limited use despite efforts by various organizations to eliminate its use entirely.

16.5 A change in any one dimension of a solid is called linear expansion.

16.6

Linear expansion is by no means restricted to the length of a solid. Any line drawn through the solid will increase in length per unit length at the rate given by its expansion coefficient α. For example, in a solid cylinder, the length, diameter, and a diagonal drawn through the solid will all increase their dimensions in the same proportion.

16.7

The symbol β (beta) is the volume expansion coefficient. It represents the change in volume per unit volume per degree change in temperature. For solid materials, it is approximately three times the linear expansion coefficient.

16.8

Say we fill the bulb of the tube in with water at 0°C so that the narrow neck is partially filled. Expansion or contraction of the water can be measured easily by observing the water level in the narrow tube. As the temperature of the water increases, the water in the tube will gradually sink, indicating a contraction.

Chapter 17 Quantity of Heat
17.1

It was originally believed that two systems reach thermal equilibrium through the transfer of a substance called caloric. The equivalence of heat and work as two forms of energy was established later by Sir James Prescott Joule.

17.2

The idea of heat as a substance must be discarded. It is not something that an object has but something that it gives up or absorbs. Heat is simply another form of energy that can be measured only in terms of the effect it produces. The SI unit of energy, the joule, is also the preferred unit for heat since heat is a form of energy. There are three older units that remain in use today, however, and they will also be treated in this text. These earlier units were based on the thermal energy required to produce a standard change. They are the calorie, the kilocalorie, and the British thermal unit. One calorie (cal) is the quantity of heat required to change the temperature of 1 gram of water through 1 Celsius degree.

17.3

The heat capacity of a body is the ratio of heat supplied to the corresponding rise in temperature of the body. Basically what this is saying is that all objects take different amounts of time to heat up.

17.4

The term heat has now been introduced as the thermal energy absorbed or released during a temperature change. The quantitative relationship between heat and temperature is best described by the concept of specific heat. The physical relationships among all these terms are now beginning to fall into place. The principle of thermal equilibrium tells us that whenever objects are placed together in an insulated enclosure, they will eventually reach the same temperature. This is the result of a transfer of thermal energy from the warmer bodies to the cooler bodies. If energy is to be conserved, we say that the heat lost by the warm bodies must equal the heat gained by the cool bodies. Basically Heat loss=heat gain. In an actual experiment, the portion of the thermometer inside the calorimeter would absorb about the same amount of heat as an extra 0.5 g of water. This quantity, called the water equivalent of the thermometer, should be added to the mass of water in an accurate experiment.

17.5

Under the proper conditions of temperature and pressure, all substances can exist in three phases, solid, liquid, or gas. In the solid phase, the molecules are held together in a rigid, crystalline structure, so the substance has a definite shape and volume. As heat is supplied, the energies of the particles in the solid gradually increase, and its temperature rises. Eventually, the kinetic energy becomes so great that some of the particles overcome the elastic forces that hold them in fixed positions. The increased separation gives them the freedom of motion that we associate with the liquid phase. At this point, the energy absorbed by the substance is used in separating the molecules more than in the solid phase. The temperature does not increase during such a change of phase. The change of phase from a solid to a liquid is called fusion, and the temperature at which this change occurs is called the melting point. The quantity of heat required to melt a unit mass of a substance at its melting point is called the latent heat of fusion for that substance. The change of phase from a liquid to a vapor is called vaporization, and the temperature associated with this change is called the boiling point of the substance. The quantity of heat required to vaporize a unit mass is called the latent heat of vaporization. As more heat is removed, the vapor returns to the liquid phase this process is referred to as condensation. Let's say the sun melts snow off a mountain, thus turning the solid into a liquid, and thus turning the liquid to a gas. With the snow liquefied and evaporated, the vapor moves on further down country side, eventually the vapor condenses forming clouds, eventually it will condenses to the point where the vapor becomes too heavy to remain airborne and falls back to Earth as precipitation. Similarly, when heat is removed from a liquid, its temperature will drop until it reaches the temperature at which it melted. As more heat is removed, the liquid returns to its solid phase. This process is called freezing or solidification The heat of solidification is exactly equal to the heat of fusion. Thus, the only distinction between freezing and melting lies in whether heat is being released or absorbed.

17.6

Whenever a substance is burned, it releases a definite quantity of heat. The quantity of heat per unit mass, or per unit volume, when the substance is burned completely is called the heat of combustion. Commonly used units are Btu per pound mass, Btu per cubic foot, calories per gram, and kilocalories per cubic meter. For example, the heat of combustion of coal is approximately 13,000 Btu/lbm. This means that each pound of coal, when completely burned, should release 13,000 Btu of heat energy.

Chapter 18 Transfer of Heat
18.1

Conduction: by molecular collisions between neighboring molecules. For example, if we hold one end of an iron rod in a fire, the heat will eventually reach our hand through the process of conduction. The increased molecular activity at the heated end is passed on from molecule to molecule until it reaches the hand. The process will continue as long as there is a difference in temperature along the rod. Conduction is the process in which heat energy is transferred by adjacent molecular collisions throughout a material medium. The medium itself does not move. Convection is the process by which heat is transferred by the actual mass motion of a fluid. Convection currents form the basis for heating and cooling most houses. When we hold our hand to the side of a fire, the primary source of heat is through thermal radiation. Radiation involves the emission or absorption of electromagnetic waves originating at the atomic level.

18.2

The proportionality constant k is a property of the material called its thermal conductivity. From the defining equation, one can see that substances with a large thermal conductivity are good conductors of heat, whereas substances of low conductivity are poor conductors, or insulators. The thermal conductivity of a substance is a measure of its ability to conduct heat and is defined by the relation. It is always wise to carry the units of each quantity throughout the entire solution of a problem. This practice will save many needless errors. For example, it is sometimes easy to forget that in USCS units, the thickness must be expressed in inches and the area in square feet. If the units of thermal conductivity are written with their numerical value during substitution, many such errors can be avoided.

18.3

Heat losses in homes and in industry are often based on the insulating properties of various composite walls. For example, one might wish to know the effects of replacing dead air spaces in walls with fiberglass insulation. In such cases, the concept of thermal resistance R has been introduced into engineering applications. The R-value of a material of thickness L and of thermal conductivity k is defined as R = L/K

18.4

Convection has been defined as the process in which heat is transferred by the actual mass motion of a material medium. A current of liquid or gas that absorbs energy at one place and then moves to another place, where it releases heat to a cooler portion of the fluid, is called a convection current. If the motion of a fluid is caused by a difference in density that accompanies a change in temperature, the current produced is referred to as natural convection. The water flowing through the glass tubing in the previous example represents a natural-convection current. When a fluid is called to move by the action of a pump or fan, the current produced is referred to as forced convection.

18.5

The term radiation refers to the continuous emission of energy in the form of electromagnetic waves originating at the atomic level. In this section, we will be concerned with thermal radiation. Objects that are efficient emitters of thermal radiation are also efficient absorbers of radiation. An object that absorbs all the radiation incident on its surface is called an ideal absorber. Such an object will also be an ideal radiator. There is no such thing as an ideal absorber; but, in general, the blacker a surface, the better it absorbs thermal energy. For example, a black shirt absorbs more of the Sun's radiant energy than a lighter shirt. Since the black shirt is also a good emitter, its external temperature will be higher than our body temperature, making us uncomfortable. An ideal absorber or an ideal radiator is sometimes referred to as a blackbody for the reasons mentioned previously. The radiation emitted from a blackbody is called blackbody radiation. Although such bodies do not actually exist, the concept is useful as a standard for comparing the emissivity of various surfaces.

Chapter 19 Thermal Properties of Matter
19.1

One of the most useful generalizations about gases is the concept of an ideal gas, whose behavior is completely unaffected by cohesive forces or molecular volumes. Of course, no real gas is ideal, but under ordinary conditions of temperature and pressure, the behavior of any gas conforms closely to the behavior of an ideal gas. Therefore, experimental observations of many real gases can lead to the derivation of general physical laws governing their thermal behavior. The degree to which any real gas obeys these relations is determined by how closely it approximates an ideal gas. He made an exhaustive study of the changes in the volume of gases as a result of changes in pressure. All other variables, such as mass and temperature, were kept constant. This finding is now know as Boyle's law. Boyle's Law: Provided that the mass and temperature of a sample of gas are held constant, the volume of the gas is inversely proportional to its absolute pressure. Charles's Law: Provided that the mass and pressure of a gas are held constant, the volume of the gas is directly proportional to its absolute temperature.

19.2

Gay-Lussac's Law: If the volume of a sample of gas remains constant, the absolute pressure of the gas is directly proportional to its absolute temperature.

19.3

Let us now consider the effect of a change in mass on the behavior of gases. If the temperature and volume of an enclosed gas are held constant, the addition of more gas will result in a proportional increase in pressure. Similarly, if the pressure and temperature are fixed, an increase in the mass will result in a proportional increase in the volume.

19.4

Although the mass of individual atoms is difficult to determine because of their size, experimental methods have been successful in measuring atomic mass. When working with macroscopic quantities, such as volume, pressure, and temperature, it is much more convenient to compare the relative masses of individual atoms. The relative atomic masses are based on the mass of a reference atom known as carbon 12. By arbitrarily assigning exactly 12 atomic mass units (u) to this atom, we have a standard for comparison of other atomic masses. The atomic mass of an element is the mass of an atom of that element compared with the mass of an atom of carbon taken as 12 atomic mass units. The definition of molecular mass follows from the definition of relative atomic mass.

19.5

R is known as the universal gas constant.

19.6

All real gases experience intermolecular forces. At rather low pressures and high temperatures, however, real gases behave much like an ideal gas. Boyle's law applies because the intermolecular forces under these conditions are practically negligible. A temperature will be reached at which the gas will just begin to liquefy under compression. The highest temperature at which this liquefaction occurs is called the critical temperature. 19.7

There are three ways in which vaporization may occur: (1) evaporation, (2) boiling, and (3) sublimation. During evaporation, vaporization occurs at the surface of a liquid as the more energetic molecules leave the surface. In the process of boiling, vaporization occurs within the body of the liquid. Sublimation occurs when a solid vaporizes without passing through the liquid phase. In each case, an amount of energy equal to the latent heat of vaporization or sublimation must be lost by the liquid or solid. Only the faster-moving particles can approach the surface with sufficient energy to overcome the retarding forces. These molecules are said to evaporate because, on leaving the liquid, they become typical gas particles. They have not changed chemically; the only difference between a liquid and its vapor is the distance between molecules. Since only the most energetic molecules are able to break away from the surface, the average kinetic energy of the molecules remaining in the liquid is reduced. Hence, evaporation is a cooling process.

19.8

When a high-energy liquid molecule breaks away from the surface, it becomes a vapor molecule and mixes with the air molecules above the liquid. These vapor molecules collide with air molecules, other vapor molecules, and the walls of the jar. The additional vapor molecules cause a rise in pressure inside the jar. The vapor molecules may also rebound back into the liquid, where they are held as liquid molecules. This process is called condensation. Eventually the rate of evaporation will equal the rate of condensation, and a condition of equilibrium will exist. Under these conditions, the space above the liquid is said to be saturated. The pressure exerted by the saturated vapor against the walls of the jar, over and above that exerted by the air molecules, is called the saturated vapor pressure. It is characteristic of the substance and the temperature but independent of the volume of the vapor. the pressure on the liquid surface is 1 atm, as it would be in an open container, the temperature at which boiling occurs is called the normal boiling point for that liquid. The normal boiling point for water is 100°C because that is the temperature at which the vapor pressure of water is 1 atm (760 mm of mercury). If the pressure on any liquid surface is lower than 1 atm, boiling will occur at a temperature lower than the normal boiling point. If the external pressure is greater than 1 atm, boiling will occur at a higher temperature.

19.9

A similar curve can be plotted for the temperatures and pressures at which a substance in the solid phase can coexist with its liquid phase. Such a curve is called a fusion curve. The fusion curve for water is represented by the line AC in the phase diagram. At any point on this curve, the rate at which ice is melting is equal to the rate at which water is freezing. Note that, as the pressure increases, the melting temperature (or freezing temperature) is lowered. A third graph, called the sublimation curve, can be plotted to show the temperatures and pressures at which a solid may coexist with its vapor.

19.10

The air in our atmosphere consists largely of nitrogen and oxygen with small amounts of water vapor and other gases. It is often useful to describe the water-vapor content of the atmosphere in terms of absolute humidity. The absolute humidity is defined as the mass of water per unit volume of air. The relative humidity is usually expressed as a percentage. The temperature to which the air must be cooled at constant pressure to produce saturation is called the dew point. Thus, if ice is placed in a glass of water, moisture will eventually collect on the outside walls of the glass when its temperature reaches the dew point.

Chapter 3 Technical Measurements and Vectors
3.1

The language of physics and technology is a universal one. If we were working on an engine and we knew that this engine had a piston which displaces 3.28 liters. We would first ask ourselves two question, what is piston displacement and what is a liter? Piston displacement is the volume the piston displaces as it moves up and down, and a liter is an easily recognizable unit of measure. Thus all mechanics would use this term and system, due to it being universal. When we look at objects in terms of length, weight, speed, time, force, and mass, we are looking at the object's physical qualities. An example would be the weight of a bar bell, the weight of a bar bell is 45 lbs. What was just said about the bar bell was the object's Magnitude. Magnitude of a physical quantity is determined by number and unit of measure. Another important note is the use of Standards, these are permanent or easily determined physical unit of the size of a physical unit. An example would be a foot, we all know that a standard foot is 12 inches long.

3.2

The international system of units is also known as SI, or what we know as the metric system. This system was developed with the idea of having a globally set standard of units of measure. However in the United States we have yet to join the rest of the world and so we still use the U.S Customary system of Units or USCS.

3.3

The SI unit, meter (m) was originally defined as one ten-millionth of the distance from the North Pole to the Equator. This measurement was changed using light emitted from krypton, however due to advancements in technology, a more accurate, and more final measurement was recorded. One meter, is now the length of path traveled by a light wave in a vacuum in a time interval of 1/299,792,458 second. This measurement is more precise and hinges on the values of the velocity (speed) of light. which is C= 2.99792458 x 10^8 m/s. This values of the velocity of light is now a standard based on Einstein's theory that the speed of light is constant. Another addition to SI is the multiples and sub-multiples for other SI units. These are used to help condense some of the larger numbers we see in physics. For instants the multiple Mega (M) is 10^6 or 1,000,000. If we were talking about power (expressed in watts) we could say 4,000,000 watts of power but that takes up room, and doesn't sound nearly as cool as 4 Megawatts of power. The inverse is true on smaller numbers, say if we were measuring something in amperes (amps) and that measurement was .000064 amps, we would use the sub-multiple mili (m) and say 0.64mA.

3.4

If we were measuring something and it came out to be, 3.42cm. the last digit is estimated and therefore is susceptible to error. the actual measurement would fall between 3.40 and 3.50 cm. to write the measurement as 3.420cm would imply greater accuracy than was justified. We say that the number has three significant figures, and we are careful not to write more numbers or zeros than are meaningful. All physical measurements are assumed to be approximate, with the last significant digit having been determined by an estimation. 4.003 has 4 significant figures, 0.34 has 2 significant figures. A significant figure is known as a reliably known digit. There exists two rules, 1; when approximate numbers are multiplied or divided, the number of significant digits in the reported result is the same as the number of significant digits in the least accurate of the factors. By "least accurate" we mean the factor lowest number of significant digits. Rule 2; when approx. numbers are added or subtracted, the number of decimal places in the result should equal the smallest number of decimal places of any term in the sum.

3.5

Whatever device we choose to take measurements with is directly determined by the physical conditions surrounding the measuring instrument.

3.6

We know that the length of 1 inch is equal to the length of 25.4 millimeters. We would write this as a 25.4mm/1in, this ratio is known as a conversion factor. Sometimes we have to use multiple units in certain quantities. Speed for example, uses both length and time, for example meters per second. If 2 quantities are to be added or subtracted they must be the same dimensions, if the quantities on both sides of an equals sign must be of the same dimensions.

3.7

Quantities that are expressed solely by number are Scalar Quantities, such as 50 km, 40ft^3. Scalar Quantities are expressed only by their magnitudes- number and unit. When quantities have a direction added to their magnitude, they become vector quantities, as in 40Km/h 30 degrees N.

3.8

The polygon method is the more useful one, since it can be readily applied to more than two vectors. The parallelogram method is useful for the addition of two vectors at a time.

3.9

The most familiar force is weight, which is the gravity exerted on every body on the Earth. Here in the U.S weight is measured in pounds (lbs) as where in SI weight is measured in Newtons (N). As a vector quantity weight is directed towards the center of the Earth. 1 N=.225lbs and 1lb = 4.45N. There are two measurable effects of forces, changing the dimensions or shape of a body, and changing a body's motion. The 1st case, if there's no resultant displacement of the body, the push or pull causing the change in shape is called Static Force. If a force changes the motion of a body it is called a dynamic force.

3.10

When 2 or more forces act at the same point on an object, they are said to be concurrent forces. The combined effect of such forces is called the resultant force. If we had two concurrent forces moving in the same direction, then the resultant force would be the sum of those two forces. For example if we applied 5N of force to an object and then added another 35N of force in the same direction and location then our resultant force would be 40N of net force (total force).

3.11

To find the resultant vector or the components of a vector, we use Right-triangle trigonometry, or Pythagorean Theorem.

3.12

Due to Trig. we will use that to make sure our final results are accurate, the only estimating that need be done, is with the vectors themselves. For example a 60 N force should be drawn as a vector three times as long as the vector for a 20 N force. The given angles should also be estimated.

Chapter 4 Translational Equilibrium and Friction
4.1

Equilibrium = Balance Friction a horizontal action in which an object sliding across another which generates heat, and causes said object to slow down. Without friction a ball rolling across the floor would never come to a stop. Newton's First law of Motion: A body at rest will remain at rest, a body in motion will remain in motion in a straight line unless acted on by an external force. This law is expressed under ideal conditions, due to friction an object ain motion will, given time, come to a stop. Another name for this law is the law of inertia, Inertia, is the property of a particle that allows it to maintain a constant state of motion or rest.

4.2

If an object remains in a constant state of motion, it requires a resultant force (f) of some amount to generate it's acceleration (a). In other words the amount of force applied to an object will generate movement. However, an object's mass (m) decreases give the amount of mass an object has. For instance if you push a small box across a table a certain amount of force will be required to cause movement. That being said if you had a larger box, you would have to exert more force on the box in order to generate movement. Newton's Second Law of Motion: The acceleration (a) of an object in the direction of a resultant force (f) is directly proportional to the magnitude of the force and inversely proportional to the mass (m). A simple equation represents this Law. Force= (Mass)(Acceleration)  F= ma
 * Note that when velocity does not change acceleration is zero. There is also no resultant force on objects at rest and moving at constant speed (a= 0).

4.3

There can be no force if two or more bodies are not involved, an object cannot begin moving simply of it's own volition. When a boxer punches a bag, his fist exerts an "action" force on the bag. However, the bag also exerts a "reaction" force back at the fist. When two objects interact the force exerted by the second body on the first (Reaction force) is equal in magnitude and opposite in direction to the force exerted by the first on the second (action force). Newton's Third Law of Motion: For every action, there must be an equal and opposite reaction.

4.4

Equilibrium exists when all external forces register as zero, meaning there is no unbalanced force causing acceleration. Therefore in Newton's 1st Law an object in equilibrium must either be at rest or be moving at constant velocity. The term Transitional Equilibrium is used to distinguish the first condition from the second condition for equilibrium, which involves rotational motion, (see Chapter 5).

4.6

see book

4.7

When a body moves while in contact with the surface of another object, friction forces oppose the relative motion. Friction is caused by the adhesion of one surface to the other and by the interlocking or irregularities in the rubbing surfaces. It is this friction that allows us to walk, brakes on a vehicle to work, etc. Friction generates heat, which can cause damage. When the space shuttle reenters the Earth's atmosphere, the friction generated between the heat shield of the shuttle and the atmosphere creates incredibly high heat, which (if the heat shield doesn't hold) will destroy the shuttle. Static friction, occurs when an object is being forced to move but the friction holds it in place. Kinetic friction, occurs when an object is moving and the friction is creating drag on the object.

Chapter 6 Uniform Acceleration
6.1

The simplest kind of motion in an object is uniform motion in a straight line. If an object covers the same distance in each successive unit of time, it is said to move with constant speed. Whether speed is constant or not, the average speed is defined by; Average speed= distance traveled/ time elapsed. Sometimes objects cannot always travel at constant velocity, certain adverse conditions may arise that cause said object to either slow down or speed up. So, we use what is called instantaneous speed. Supposed we used a line with it's start marked A, and B being the finish point or destination of the object. We would use an arbitrary point C to represent the moment of instantaneous speed.

6.2

If an object is not moving at a constant speed but, speeding up, we say it's accelerating. Acceleration is calculated as Acceleration = change in time/ time interval.

6.3

The simplest kind of acceleration is motion in a straight line in which the speed changes at a constant rate. This kind of special motion is called uniform acceleration or constant acceleration. When speed is reduced we call deceleration, but this term is problematic due to the fact that acceleration a =-1.39m/s^2, which really means that velocity becomes more negative by said amount every second. So the term deceleration is incorrect, acceleration means a change in velocity, which can mean either an increase or a decrease in speed.

6.4 & 6.5 See book for mathematics and graph details.

6.6

Generally we consider upward motion to be positive and downward motion to be negative. If a child were to throw a baseball in the air at a rate of 2m/s^2 it would accelerate in a positive direction, until eventually it stopped and begins moving in a negative direction eventually reaching the same speed with which it was thrown. Once an object is thrown in a positive direction, the following conventions will determine the signs of velocity, displacement, and acceleration. Displacement is positive or negative depending on the location or coordinate of position of the object relative to its zero position. Velocity is positive or negative depending on whether the direction of motion is with or against the chosen positive direction. Acceleration is positive or negative depending on whether the resultant force is with or against the positive direction.

6.7

Much of what we know today about falling objects came from Galileo Galilee. He was the first to deduce that in the absence of friction all bodies, large or small, heavy or light, fall to Earth with the same acceleration. Assuming we eliminated air friction, all falling bodies accelerate under the term gravitational acceleration. At sea level and at 45 degrees latitude this acceleration has been measure to be 9.806 m/s^2 and is denoted by g. This form of acceleration is a constant one.

6.8

If an object is launched without being under its own power, we call it a projectile.

6.9

If a projectile is fired horizontally, its motion can best be described by considering its horizontal and vertical motion separately. For instance, it a ball was projected horizontally, while at the same time another ball was dropped vertically. they would both land at the same time.

Chapter 7 Newton's 2nd Law
7.1

A machine using a straight rail, covered with air holes, where air is force through the rail, thus allowing anything that rides on the rail, to actually ride on a cushion of air. A device such as this one, would be used to measure how force acts on a object of a given mass, without worrying about friction. The equation for Newton's second Law is Resultant force= mass x acceleration. 1lb=4.448 N 1 slug= 14.59 kg.

7.2

Before we can use newton's second law, we must be able to decern the difference between weight and mass. Generally we see the unit of force, its often used as a mass unit. The Kilogram is a unit of mass, it is often used in industry as a unit of force. Mass is a universal constant equal to the ratio of a body's weight to the gravitational acceleration due to its weight. Weight is the force of gravitational attraction and varies depending on the acceleration of gravity.

7.3

According to Newton's Second law, a resultant force always produces an acceleration in the direction of the resultant force.

7.4

When solving a problem involving the 2nd law of motion, use the following.

1. Read the problem carefully and then draw and label a rough sketch

2. Indicate all give information and statae what is to be found

3. Construct a free-body diagram for each object undergoing acceleration and choose an x or y axis along the continuous line of motion

4. Indicate a consistent choice for the positive direction along the continuous line of motion

5. Be careful not to confuse the weight of an object with its mass: W = mg  m = W/g

6. From the free-body diagram(s), determine the resultant force along the assumed positive line of motion

7. Determine the total mass of the system

8. Set resultant force equal to the total mass times the acceleration a.

9. Substitute all given quantities and solve for the unknown.

The mass of the space shuttle is 2030 tons, at lift off. It takes 2,650,000 pounds of force to lift the shuttle off the ground. 480 seconds later the shuttle has reached Earth orbit.

Chapter 8 Work, Energy and Power
8.1

The capacity for doing work is called energy, and the rate at which accomplished is defined as power. When the space shuttle takes off, it requires a huge amount of force, to achieve lift off. Now, the fuel stored in the solid fuel booster rockets that the shuttle is attached to, is the energy portion. The rate at which the shuttle takes off is the power. So, the fact that shuttle ascended from the ground and reached orbit is called work. For work to be done three things need to happen...

1. There must be an applied force

2. The force must act through a certain distance, called the displacement.

3. The force must have a component along the displacement.

Work is a scalar quantity equal to the magnitudes of the displacement and the component of the force in the direction of the displacement. Joule, a SI unit that is the unit of measure for power.

8.2

The term resultant work (total work) comes from the multiple forces that effect an object.

8.3

There are several forms of energy in mechanics there are two major forms. Kinetic Energy K: energy possessed by a body by virtue of its motion. Potential Energy U: energy possessed by a system by virtue of position or condition. So lets say we have a gun, the powder store in the bullet is the potential energy. Once the bullet is fired the, it impacts a target. The energy or force it hit the target with is the bullet's kinetic energy.

8.4

The resultant work done on a mass by a constant force acting through a distance is equal to its change in kinetic energy. This is what we call work-energy theorem. We can use this theorem to find the average force of an object.

8.5

If we had a crane and hold a 2,000 lb object 50 feet in the air, it has potential energy, due to the body-Earth system. The gravitational potential energy for an air plane is significantly different than a mountain, sky scraper, or the ocean. The energy is unchanging,the energy in the stone used in the building of the Pyramids of Giza in Egypt which were built 2500 years ago, still have the same potential energy.

8.6

Conservation of mechanical energy: in the absence of air resistance or other dissipative forces, the sum of the potential and kinetic energies is a constant, provided that no energy is added to the system.

8.7

Lets say a car is moving down the road with 1000 j of force, it loses 400j due to friction, so it has 600j left for the velocity of the car. Initial total energy = final total energy + losses due to friction.

Conservation of Energy: The total energy of a system is always constant, although energy changes from one form to another may occur within the system.

8.8

In the definition of work, time is not involved in any way. But when calculating power it is. Power = work/time The SI unit for power is the joule per second, which was renamed the watt.

Chapter 16 Temperature and Expansion
16.1

Thermal energy represents the total internal energy of an object: the sum of its molecular kinetic and potential energies. When a meteorite impacts the Earth, it is super heated by falling through the atmosphere. After impact, it eventually cools and becomes stable. We call this Thermal Equilibrium. Seeing as classical mechanics alone cannot accurately describe the changes in thermal energy, we must use a different property to determine if they will be at thermal equilibrium with other objects, we call this property Temperature.

16.2

A device known as a thermometer is used to measure temperature. Two temps that can be reproduced easily are, lower fixed point and upper fixed point. The lower fixed point (ice point) is the temp at which water and ice coexist in thermal equilibrium under a pressure of 1atm. The upper fixed point (steam point) is the temp at which water and steam coexist n equilibrium under a pressure of 1 atm. Anders Celsius (1701-1744), a Swedish astronomer. The Celsius scale arbitrarily assigned the number 0 to the ice point and the number 100 to the steam point. Each division or unit on the scale is called a degree (°). For example, room temperature is often taken as 20°C, which is read as twenty degrees Celsius. Another scale for measuring temperature was developed in 1714 by Gabriel Daniel Fahrenheit. The development of this scale was based on the choice of different fixed points. Fahrenheit chose the temperature of a freezing solution of salt water as his lower fixed point and assigned it the number and unit of 0°F. Relating the Fahrenheit scale to the universally accepted fixed points on the Celsius scale, it can be shown that 0 and 100°C correspond to 32 and 212°F.

16.3

While mercury is common to the thermometer, it is not as accurate, the most accurate are gas thermometers, where the gas expands in the same way when heated. There are two kinds of gas thermometers. One kind maintains a constant pressure and utilizes the increases in volume as an indicator. This type is called a constant-pressure thermometer. The other kind, called a constant-volume thermometer, measures the increase in pressure as a function of temperature.

16.4

Both Celsius and Fahrenheit have limitations, neither of these have a true 0 degree temp. Absolute Zero is the point where all thermal energy stops, it is measured as -273.15 degrees C or -460 degrees F. An absolute temperature scale has as its zero point the absolute zero of temperature. One such scale was devised by Lord Kelvin (1824–1907). The standard interval on this scale, the kelvin, has been adopted by the international (SI) metric system as the base unit for temperature measurement. The interval on the Kelvin scale represents the same change in temperature as the Celsius degree. Thus, an interval of 5 K (reads “five kelvins”) is exactly the same as 5 C°. The triple point of water, which is the single temperature and pressure at which water, water vapor, and ice can coexist in thermal equilibrium. To remain consistent with earlier measurements, the temperature for the triple point of water was set at exactly 273.16 K. The kelvin is now defined as the fraction 1/273.16 of the temperature of the triple point of water. A second absolute scale, called the Rankine scale, remains in very limited use despite efforts by various organizations to eliminate its use entirely. The Rankine degree is included here only for historical purposes. Its absolute zero point is −460°F, and the degree interval is the same as the Fahrenheit interval. For example, 32°F corresponds to 492°R, and 212°F corresponds to 672°R.

16.5 A change in any one dimension of a solid is called linear expansion.

16.6

Linear expansion is by no means restricted to the length of a solid. Any line drawn through the solid will increase in length per unit length at the rate given by its expansion coefficient α. For example, in a solid cylinder, the length, diameter, and a diagonal drawn through the solid will all increase their dimensions in the same proportion.

16.7

The symbol β (beta) is the volume expansion coefficient. It represents the change in volume per unit volume per degree change in temperature. For solid materials, it is approximately three times the linear expansion coefficient.

16.8

Say we fill the bulb of the tube in with water at 0°C so that the narrow neck is partially filled. Expansion or contraction of the water can be measured easily by observing the water level in the narrow tube. As the temperature of the water increases, the water in the tube will gradually sink, indicating a contraction. The contraction continues until the temperatures of the bulb and the water are 4°C. As the temperature increases above 4°C, the water reverses its direction and rises continuously, indicating the normal expansion with an increase in temperature. This means that water has its minimum volume and its maximum density at 4°C.

Chapter 17 Quantity of Heat
17.1

It was originally believed that two systems reach thermal equilibrium through the transfer of a substance called caloric. The equivalence of heat and work as two forms of energy was established later by Sir James Prescott Joule.

17.2

The idea of heat as a substance must be discarded. It is not something that an object has but something that it gives up or absorbs. Heat is simply another form of energy that can be measured only in terms of the effect it produces. The SI unit of energy, the joule, is also the preferred unit for heat since heat is a form of energy. There are three older units that remain in use today, however, and they will also be treated in this text. These earlier units were based on the thermal energy required to produce a standard change. They are the calorie, the kilocalorie, and the British thermal unit. One calorie (cal) is the quantity of heat required to change the temperature of 1 gram of water through 1 Celsius degree. One kilocalorie (kcal) is the quantity of heat required to change the temperature of 1 kilogram of water through 1 Celsius degree (kcal = 1000 cal). One British thermal unit (Btu) is the quantity of heat required to change the temperature of 1 standard pound (lb) through 1 Fahrenheit degree. 1 lb = 454 g = 0.454 kg

17.3

The heat capacity of a body is the ratio of heat supplied to the corresponding rise in temperature of the body. Basically what this is saying is that all objects take different amounts of time to heat up.

17.4

The term heat has now been introduced as the thermal energy absorbed or released during a temperature change. The quantitative relationship between heat and temperature is best described by the concept of specific heat. The physical relationships among all these terms are now beginning to fall into place. The principle of thermal equilibrium tells us that whenever objects are placed together in an insulated enclosure, they will eventually reach the same temperature. This is the result of a transfer of thermal energy from the warmer bodies to the cooler bodies. If energy is to be conserved, we say that the heat lost by the warm bodies must equal the heat gained by the cool bodies. Basically Heat loss=heat gain. In an actual experiment, the portion of the thermometer inside the calorimeter would absorb about the same amount of heat as an extra 0.5 g of water. This quantity, called the water equivalent of the thermometer, should be added to the mass of water in an accurate experiment.

17.5

Under the proper conditions of temperature and pressure, all substances can exist in three phases, solid, liquid, or gas. In the solid phase, the molecules are held together in a rigid, crystalline structure, so the substance has a definite shape and volume. As heat is supplied, the energies of the particles in the solid gradually increase, and its temperature rises. Eventually, the kinetic energy becomes so great that some of the particles overcome the elastic forces that hold them in fixed positions. The increased separation gives them the freedom of motion that we associate with the liquid phase. At this point, the energy absorbed by the substance is used in separating the molecules more than in the solid phase. The temperature does not increase during such a change of phase. The change of phase from a solid to a liquid is called fusion, and the temperature at which this change occurs is called the melting point. The quantity of heat required to melt a unit mass of a substance at its melting point is called the latent heat of fusion for that substance. The change of phase from a liquid to a vapor is called vaporization, and the temperature associated with this change is called the boiling point of the substance. The quantity of heat required to vaporize a unit mass is called the latent heat of vaporization. As more heat is removed, the vapor returns to the liquid phase this process is referred to as condensation. Let's say the sun melts snow off a mountain, thus turning the solid into a liquid, and thus turning the liquid to a gas. With the snow liquefied and evaporated, the vapor moves on further down country side, eventually the vapor condenses forming clouds, eventually it will condenses to the point where the vapor becomes too heavy to remain airborne and falls back to Earth as precipitation. Similarly, when heat is removed from a liquid, its temperature will drop until it reaches the temperature at which it melted. As more heat is removed, the liquid returns to its solid phase. This process is called freezing or solidification The heat of solidification is exactly equal to the heat of fusion. Thus, the only distinction between freezing and melting lies in whether heat is being released or absorbed. Under the proper conditions of temperature and pressure, it is possible for a substance to change from the solid phase directly to the gaseous phase without passing through the liquid phase. This process is referred to as sublimation. Solid carbon dioxide (dry ice), iodine, and camphor (mothballs) are examples of substances that are known to sublime at normal temperatures. The quantity of heat absorbed per unit mass in changing from a solid to a vapor is called the heat of sublimation.

17.6

Whenever a substance is burned, it releases a definite quantity of heat. The quantity of heat per unit mass, or per unit volume, when the substance is burned completely is called the heat of combustion. Commonly used units are Btu per pound mass, Btu per cubic foot, calories per gram, and kilocalories per cubic meter. For example, the heat of combustion of coal is approximately 13,000 Btu/lbm. This means that each pound of coal, when completely burned, should release 13,000 Btu of heat energy.

Chapter 18 Transfer of Heat
18.1

Conduction: by molecular collisions between neighboring molecules. For example, if we hold one end of an iron rod in a fire, the heat will eventually reach our hand through the process of conduction. The increased molecular activity at the heated end is passed on from molecule to molecule until it reaches the hand. The process will continue as long as there is a difference in temperature along the rod. Conduction is the process in which heat energy is transferred by adjacent molecular collisions throughout a material medium. The medium itself does not move. Convection is the process by which heat is transferred by the actual mass motion of a fluid. Convection currents form the basis for heating and cooling most houses. When we hold our hand to the side of a fire, the primary source of heat is through thermal radiation. Radiation involves the emission or absorption of electromagnetic waves originating at the atomic level. These waves travel at the speed of light (3 × 108 m/s) and require no material medium for their passage. Radiation is the process by which heat is transferred by electromagnetic waves.

18.2

The proportionality constant k is a property of the material called its thermal conductivity. From the defining equation, one can see that substances with a large thermal conductivity are good conductors of heat, whereas substances of low conductivity are poor conductors, or insulators. The thermal conductivity of a substance is a measure of its ability to conduct heat and is defined by the relation. It is always wise to carry the units of each quantity throughout the entire solution of a problem. This practice will save many needless errors. For example, it is sometimes easy to forget that in USCS units, the thickness must be expressed in inches and the area in square feet. If the units of thermal conductivity are written with their numerical value during substitution, many such errors can be avoided.

18.3

Heat losses in homes and in industry are often based on the insulating properties of various composite walls. For example, one might wish to know the effects of replacing dead air spaces in walls with fiberglass insulation. In such cases, the concept of thermal resistance R has been introduced into engineering applications. The R-value of a material of thickness L and of thermal conductivity k is defined as R = L/K

18.4

Convection has been defined as the process in which heat is transferred by the actual mass motion of a material medium. A current of liquid or gas that absorbs energy at one place and then moves to another place, where it releases heat to a cooler portion of the fluid, is called a convection current. If the motion of a fluid is caused by a difference in density that accompanies a change in temperature, the current produced is referred to as natural convection. The water flowing through the glass tubing in the previous example represents a natural-convection current. When a fluid is called to move by the action of a pump or fan, the current produced is referred to as forced convection.

18.5

The term radiation refers to the continuous emission of energy in the form of electromagnetic waves originating at the atomic level. Gamma rays, x rays, light waves, infrared rays, radio waves, and radar waves are all examples of electromagnetic radiation; they differ only in their wavelength. In this section, we will be concerned with thermal radiation. Objects that are efficient emitters of thermal radiation are also efficient absorbers of radiation. An object that absorbs all the radiation incident on its surface is called an ideal absorber. Such an object will also be an ideal radiator. There is no such thing as an ideal absorber; but, in general, the blacker a surface, the better it absorbs thermal energy. For example, a black shirt absorbs more of the Sun's radiant energy than a lighter shirt. Since the black shirt is also a good emitter, its external temperature will be higher than our body temperature, making us uncomfortable. An ideal absorber or an ideal radiator is sometimes referred to as a blackbody for the reasons mentioned previously. The radiation emitted from a blackbody is called blackbody radiation. Although such bodies do not actually exist, the concept is useful as a standard for comparing the emissivity of various surfaces.

Chapter 19 Thermal Properties of Matter
19.1

One of the most useful generalizations about gases is the concept of an ideal gas, whose behavior is completely unaffected by cohesive forces or molecular volumes. Of course, no real gas is ideal, but under ordinary conditions of temperature and pressure, the behavior of any gas conforms closely to the behavior of an ideal gas. Therefore, experimental observations of many real gases can lead to the derivation of general physical laws governing their thermal behavior. The degree to which any real gas obeys these relations is determined by how closely it approximates an ideal gas. The first experimental measurements of the thermal behavior of gases were made by Robert Boyle (1627-1691). He made an exhaustive study of the changes in the volume of gases as a result of changes in pressure. All other variables, such as mass and temperature, were kept constant. In 1660, Boyle demonstrated that the volume of a gas is inversely proportional to its pressure. In other words, doubling the volume decreases the pressure to one-half its original value. This finding is now know as Boyle's law. Boyle's Law: Provided that the mass and temperature of a sample of gas are held constant, the volume of the gas is inversely proportional to its absolute pressure. Charles's Law: Provided that the mass and pressure of a gas are held constant, the volume of the gas is directly proportional to its absolute temperature.

19.2

Gay-Lussac's Law: If the volume of a sample of gas remains constant, the absolute pressure of the gas is directly proportional to its absolute temperature.

19.3

Let us now consider the effect of a change in mass on the behavior of gases. If the temperature and volume of an enclosed gas are held constant, the addition of more gas will result in a proportional increase in pressure. Similarly, if the pressure and temperature are fixed, an increase in the mass will result in a proportional increase in the volume.

19.4

Although the mass of individual atoms is difficult to determine because of their size, experimental methods have been successful in measuring atomic mass. When working with macroscopic quantities, such as volume, pressure, and temperature, it is much more convenient to compare the relative masses of individual atoms. The relative atomic masses are based on the mass of a reference atom known as carbon 12. By arbitrarily assigning exactly 12 atomic mass units (u) to this atom, we have a standard for comparison of other atomic masses. The atomic mass of an element is the mass of an atom of that element compared with the mass of an atom of carbon taken as 12 atomic mass units. The definition of molecular mass follows from the definition of relative atomic mass.

19.5

R is known as the universal gas constant.

19.6

All real gases experience intermolecular forces. At rather low pressures and high temperatures, however, real gases behave much like an ideal gas. Boyle's law applies because the intermolecular forces under these conditions are practically negligible. A temperature will be reached at which the gas will just begin to liquefy under compression. The highest temperature at which this liquefaction occurs is called the critical temperature. 19.7

There are three ways in which vaporization may occur: (1) evaporation, (2) boiling, and (3) sublimation. During evaporation, vaporization occurs at the surface of a liquid as the more energetic molecules leave the surface. In the process of boiling, vaporization occurs within the body of the liquid. Sublimation occurs when a solid vaporizes without passing through the liquid phase. In each case, an amount of energy equal to the latent heat of vaporization or sublimation must be lost by the liquid or solid. Only the faster-moving particles can approach the surface with sufficient energy to overcome the retarding forces. These molecules are said to evaporate because, on leaving the liquid, they become typical gas particles. They have not changed chemically; the only difference between a liquid and its vapor is the distance between molecules. Since only the most energetic molecules are able to break away from the surface, the average kinetic energy of the molecules remaining in the liquid is reduced. Hence, evaporation is a cooling process. (If you place a few drops of alcohol on the back of your hand, you will feel a cooling sensation.) The rate of evaporation is affected by the temperature of the liquid, the number of molecules above the liquid (the pressure), the exposed surface area, and the extent of ventilation.

19.8

When a high-energy liquid molecule breaks away from the surface, it becomes a vapor molecule and mixes with the air molecules above the liquid. These vapor molecules collide with air molecules, other vapor molecules, and the walls of the jar. The additional vapor molecules cause a rise in pressure inside the jar. The vapor molecules may also rebound back into the liquid, where they are held as liquid molecules. This process is called condensation. Eventually the rate of evaporation will equal the rate of condensation, and a condition of equilibrium will exist. Under these conditions, the space above the liquid is said to be saturated. The pressure exerted by the saturated vapor against the walls of the jar, over and above that exerted by the air molecules, is called the saturated vapor pressure. It is characteristic of the substance and the temperature but independent of the volume of the vapor. the pressure on the liquid surface is 1 atm, as it would be in an open container, the temperature at which boiling occurs is called the normal boiling point for that liquid. The normal boiling point for water is 100°C because that is the temperature at which the vapor pressure of water is 1 atm (760 mm of mercury). If the pressure on any liquid surface is lower than 1 atm, boiling will occur at a temperature lower than the normal boiling point. If the external pressure is greater than 1 atm, boiling will occur at a higher temperature.

19.9

A similar curve can be plotted for the temperatures and pressures at which a substance in the solid phase can coexist with its liquid phase. Such a curve is called a fusion curve. The fusion curve for water is represented by the line AC in the phase diagram. At any point on this curve, the rate at which ice is melting is equal to the rate at which water is freezing. Note that, as the pressure increases, the melting temperature (or freezing temperature) is lowered. A third graph, called the sublimation curve, can be plotted to show the temperatures and pressures at which a solid may coexist with its vapor.

19.10

The air in our atmosphere consists largely of nitrogen and oxygen with small amounts of water vapor and other gases. It is often useful to describe the water-vapor content of the atmosphere in terms of absolute humidity. The absolute humidity is defined as the mass of water per unit volume of air. The relative humidity is usually expressed as a percentage. The temperature to which the air must be cooled at constant pressure to produce saturation is called the dew point. Thus, if ice is placed in a glass of water, moisture will eventually collect on the outside walls of the glass when its temperature reaches the dew point.

Glossary
The international system of units is called Système International d'Unités (SI) and is essentially the same as what we have come to know as the metric system.

Scalar quantities can be described totally by a number and a unit. Only the magnitudes are of interest in an area of 12 m2, a volume of 40 ft3, or a distance of 50 km.

A vector quantity is specified completely by a magnitude and a direction. It consists of a number, a unit, and a direction. Examples are displacement (20 m, N) and velocity (40 mi/h, 30°N of W).

The polygon method is the more useful one, since it can be readily applied to more than two vectors.

The parallelogram method is useful for the addition of two vectors at a time.

Weight the gravitational attraction exerted on every body by the Earth.

Static force when there is no resultant displacement of the body, the push or pull causing the change in shape

If a force changes the motion of a body, it is called a dynamic force.

When two or more forces act at the same point on an object, they are said to be concurrent forces. The combined effect of such forces is called the resultant force.

Newton's first law: A body at rest remains at rest and a body in motion remains in uniform motion in a straight line unless acted on by an external unbalanced force.

Newton's second law: The acceleration a of an object in the direction of a resultant force F, is directly proportional to the magnitude of the force and inversely proportional to the mass m.

Newton's third law: For every action force there must be an equal and opposite reaction force.

The term translational equilibrium is used to distinguish the first condition from the second condition for equilibrium, which involves rotational motion.

Instantaneous speed is a scalar quantity representing the speed at the instant the car is at an arbitrary point C. It is, therefore, the time rate of change in distance.

The instantaneous velocity is a vector quantity representing the velocity vi at any point C. It is the time rate of change in displacement.

This resistance to a change in motion is a property of a body called its inertia.

An object launched into space without motive power of its own is called a projectile.

The newton is declared the SI unit of force.

The weight of any body is the force with which the body is pulled vertically downward by gravity.

Mass is a universal constant equal to the ratio of a body's weight to the gravitational acceleration due to its weight.

The capacity for doing work will be defined as energy, and the rate at which it is accomplished will be defined as power.

Kinetic Energy K: Energy possessed by a body by virtue of its motion.

Potential Energy U: Energy possessed by a system by virtue of position or condition

Conservation of Mechanical Energy: In the absence of air resistance or other dissipative forces, the sum of the potential and kinetic energies is a constant, provided that no energy is added to the system.

Conservation of Energy: The total energy of a system is always constant, although energy changes from one form to another may occur within the system.

internal energy is related to the hotness or coldness of a body, it is often referred to as thermal energy.

The transfer of thermal energy that is due only to a difference in temperature is defined as heat.

The lower fixed point (ice point) is the temperature at which water and ice coexist in thermal equilibrium under a pressure of 1 atm.

The upper fixed point (steam point) is the temperature at which water and steam coexist in equilibrium under a pressure of 1 atm.

The Celsius scale arbitrarily assigned the number 0 to the ice point and the number 100 to the steam point.

Each division or unit on the scale is called a degree (°).

Fahrenheit scale to the universally accepted fixed points on the Celsius scale, it can be shown that 0 and 100°C correspond to 32 and 212°F.

The interval on the Kelvin scale represents the same change in temperature as the Celsius degree. Thus, an interval of 5 K (reads “five kelvins”) is exactly the same as 5 C°

. The change of phase from a solid to a liquid is called fusion, and the temperature at which this change occurs is called the melting point.

The change of phase from a liquid to a vapor is called vaporization

the temperature associated with this change is called the boiling point of the substance.

The quantity of heat required to vaporize a unit mass is called the latent heat of vaporization.

As more heat is removed, the vapor returns to the liquid phase. This process is referred to as condensation.

As more heat is removed, the liquid returns to its solid phase. This process is called freezing or solidification The heat of solidification is exactly equal to the heat of fusion.

The quantity of heat absorbed per unit mass in changing from a solid to a vapor is called the heat of sublimation.

The quantity of heat per unit mass, or per unit volume, when the substance is burned completely is called the heat of combustion.

Conduction is the process in which heat energy is transferred by adjacent molecular collisions throughout a material medium.

Convection is the process by which heat is transferred by the actual mass motion of a fluid.

Radiation is the process by which heat is transferred by electromagnetic waves.

The thermal conductivity of a substance is a measure of its ability to conduct heat and is defined by the relation

A current of liquid or gas that absorbs energy at one place and then moves to another place, where it releases heat to a cooler portion of the fluid, is called a convection current.

Thermal radiation consists of electromagnetic waves emitted or absorbed by a solid, liquid, or gas by virtue of its temperature.

An object that absorbs all the radiation incident on its surface is called an ideal absorber. Such an object will also be an ideal radiator.

An ideal absorber or an ideal radiator is sometimes referred to as a blackbody for the reasons mentioned previously. The radiation emitted from a blackbody is called blackbody radiation. Although such bodies do not actually exist, the concept is useful as a standard for comparing the emissivity of various surfaces.

The law covering this phenomenon is known as Prevost's law of heat exchange: A body at the same temperature as its surroundings radiates and absorbs heat at the same rates.

Boyle's Law: Provided that the mass and temperature of a sample of gas are held constant, the volume of the gas is inversely proportional to its absolute pressure.

Charles's Law: Provided that the mass and pressure of a gas are held constant, the volume of the gas is directly proportional to its absolute temperature.

Gay-Lussac's Law: If the volume of a sample of gas remains constant, the absolute pressure of the gas is directly proportional to its absolute temperature.

Although the mass of individual atoms is difficult to determine because of their size, experimental methods have been successful in measuring atomic mass.

The highest temperature at which this liquefaction occurs is called the critical temperature.

Sublimation occurs when a solid vaporizes without passing through the liquid phase.

A similar curve can be plotted for the temperatures and pressures at which a substance in the solid phase can coexist with its liquid phase. Such a curve is called a fusion curve.

A third graph, called the sublimation curve, can be plotted to show the temperatures and pressures at which a solid may coexist with its vapor.

The point A, at which all three curves intersect, is called the triple point for water

The absolute humidity is defined as the mass of water per unit volume of air.

Units
Length       Meter (m) (SI)                         Foot (ft) (USCS)

Mass         Kilogram (kg) (SI)                    Slug (slug)(USCS)

Time          Second (s) (SI)                          Second (s)(USCS)

Force (weight) Newton (N) (SI)                   Pound (lb)(USCS)

Temperature  Kelvin (K) / Celsius (C) (SI)      Fahrenheit (F)(USCS)

Acronyms
A area

a acceleration

C capacitance

c specific heat capacity

d distance

E energy

F force

f frequency

G gravitational Constant

g acceleration

K kinetic energy

m mass

P power

P momentum

Q heat

q electric Charge

T period

t time

U potential Energy

V voltage

v velocity

α alpha

β Beta

∆ Delta Change in

∑ Equilibrium

Reference
Angry Birds: Angry Birds Gameplay Projectile motion example.

Half Life 2: Gravity Gun: Zero point energy field manipulator... Gravity gun This device Should not work this way!

Halo 4: Railgun: Rail gun Shows us what a friction-less projectile fired magnetically can do. Also show us kinetic energy in action.

Alien vs Predator: Measuring heat: Predator See what infrared vision looks like, and how the galaxy's greatest hunters measure heat.

The Laws of Physics in Cartoons: Looney physics

Space Shuttle Launch: Acceleration: Discovery Launch

Friction: Apollo !3 Re-entry

Mass Effect interprets Newton's law Sir Issac Newton is the deadliest s.o.b in space

Bad physics in star wars

Equations
Unit conversions

1 3/16in =1.19in.

1in. /25.4 mm = 1

(1.19in.)(1in./25.4mm)= (1.19in./25.4mm)(in^2/mm) WRONG!

(1.19in.)(25.4/1in.)= (1.19)(25.4)/1 = 30.2mm CORRECT

Resultant Force 20N + 15N = 35N

Newton's 2nd law Force= mass x acceleration or F=ma

Average speed= Distance traveled/ time elapsed

a= Vf-Vo/t

Work = force component x displacement

Heat Capacity = Q / change in temp.

Heat lost = Heat Gained

Thermal Resistance R= l/k

Relative humidity = actual vapor pressure/ saturated vapor pressure

Websites
hyperphysics.phy-astr.gsu.edu/hbase/frict.htm

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp.html

http://www.physicsclassroom.com/class/thermalP/u18l1e.cfm

http://web.utk.edu/~cnattras/Physics221Spring2013/modules/m12/materials.htm

http://www.physicsclassroom.com/class/vectors/u3l2c2.cfm

http://www.physicsclassroom.com/class/thermalP/u18l2b.cfm