What would a comparison of work and kinetic energy be?

Question

We had to build mousetrap cars and we have to explain the comparison between the calculated amount of work done to set the trap and the kinetic energy of the car. Is it that if our cars were 100% efficient the kinetic energy would be equal to the amount of work done?

Answer 1

That's absolutely correct. It's called the principle of work-energy equivalence. Any time 'work' is done, 'energy' is expended to change something, and that change represents the work done. The energy you used to 'set' the trap was stored in the spring as potential energy. As the mousetrap closed and propelled the car, that potential energy was being converted to kinetic energy. And when energy is converted from one form to another, 'work' is being done. Even including friction, the difference between the final kinetic energy of the car and the initial work done on the mousetrap would be exactly equal to the energy 'lost' to frictional heating.
Once you start to 'see' what's going on with work and energy, you'll never see the World in quite the same way again. It's very kewl stuff ☺

Doug

Answer 2

...enter the Watt... That's all you need to know. Look it up on Wikipedia.

http://en.wikipedia.org/wiki/Watt