User:Junmarjun/sandbox

Equilibrium means all the forces and torques are balanced (the net total is zero), so there is no change in velocity or rotational velocity.

Anything just sitting around (not moving, so obviously not accelerating) is in equilibrium. Anything moving and/or spinning at a constant rate is in equilibrium, too.

An equilibrium is stable if you can disturb the system and it is pushed back to its original state. A ball in a hole is stable. You can kick it a little and it doesn't go anywhere--it just falls back in.

An equilibrium is unstable if you disturb a system and the disturbance causes the system to go further from equilibrium. A ball balanced on top of a hill is unstable. You kick it and it rolls off.

More often than not, things in equilibrium are stable. If they aren't, they don't stay in equilibrium. So if you are looking for balls, you'll have more luck looking in holes than on top of hills.

Neutral equilibrium (which doesn't come up often) is like a ball on flat ground. You kick it and it keeps rolling at a constant speed.