User:Sandra.bitelli/PHYS100: Energy Consumption Comparison of Washing your Car

Problem Statement
We will be attempting to solve the problem of whether it is more energy efficient to wash your car at home or go to a car wash, and how much more efficient it is. We will also briefly discuss which is more harmful to the environment.

Case Description
Clark has a 2010 Nissan 350Z that he washes once a week, religiously. He usually goes to the local Shell, 5 km away, to wash his car at the commercial car wash. But, with his new interest in environmental studies and his limited budget, he wonders if it would be more cost effective and environmentally friendly to wash his car by hand. He decides to calculate the amount of energy used by a commercial car wash versus washing the car at home. He then researches on which process uses less water to make his final decision on which method is less harmful to the environment.

Project Goals
Determine:
 * 1) The amount of energy needed to drive to the car wash versus staying home
 * 2) The amount of energy needed to power a car wash versus energy needed by our bodies to physically wash the car
 * 3) The amount of water used and the effect on the environment in both situations
 * 4) Overall which is a better choice based on what was learned

Research Information

 * For an hour of washing the car, the average 75kg person will expend 337kCal of energy
 * Wattage used for a water pump is 3000W
 * 1Hp = 0.7456KwH
 * An average electric car wash has a 355-430Jp motor running it depending on the amount of air dryers.
 * The mass of the Nissan 350Z is 1516 kg
 * The mass of the Nissan 350Z is 1516 kg

Model
Models of both our car and our electrical car wash.

By Hand:
 * The person will use about 337kCals and the energy of the hose 3000W, washing the car by hand for one hour.

Assumptions
Assumptions for washing the car at home: Assumptions for going to a car wash:
 * Chemicals used will be the same as the chemicals used at the car wash
 * An average person will expend constant (consistent) energy throughout the car washing process
 * It will take him an hour to wash his own car
 * He is 75kg
 * He is 75kg
 * Chemicals used will be the same as the chemicals used while washing the car at home
 * He is driving 50km/hr to the car wash and it is 5 km away
 * He does not encounter any traffic on route to the car wash
 * Driving conditions are ideal; there are no hills on route to the car wash
 * There is negligible friction and air resistance while driving; negligible thermal energy
 * The car wash has an average 400Hp motor running the system (easy amount to use for calculations between the given values of 355 and 430Hp)
 * The car wash takes 10 minutes to complete the cycle
 * The car wash takes 10 minutes to complete the cycle

Calculations
337.3kCal x 4.184 = 1411kJ 3 000J/s 3 600s/hr 3 000 x 3 600 = 10 800 000J 10 800 000J ÷ 1 000 = 10 800kJ 1 411kJ + 10 800kJ = 12 211kJ
 * Energy consumption for person washing a car:
 * Energy consumption for the hose:
 * Total Energy used for washing the car at home:

1Hp = 0.7456KwH 0.7456KwH x 400Hp = 298.2KwH 298.24KwH = 1 073 664kJ For the 10 minute cycle: 1 073 644kJ ÷ 6 = 178 944kJ t = 5km ÷ 50km/hr = 0.1hr 0.1hr x 60mins = 6 mins Kinetic E = (1/2)*m*v^2 E = (1/2)*(1516 kg)*(50^2) E = 195 000 J = 195 kJ         178 944 kJ + 195 kJ = 179 139 kJ
 * Energy consumption of a car wash for one hour:
 * Time it takes to drive to the car wash:
 * Energy consumption for driving to the car wash:
 * Total energy for using the car wash:

Interpretation of Results
We had assumed that the total energy consumption would be much higher for using a car wash versus washing your own car due to the following:
 * the fact that energy would be used driving to and from the car wash station
 * the car wash uses machinery which uses more energy than a normal person
 * the car wash uses machinery which uses more energy than a normal person