If a car and a truck are moving with the same kinetic energy, and the same braking force is applied to stop them, which one will stop first, car or truck?

Answar:

Since both the vehicles are having same kinetic energy, change in kinetic energy will be same. Thus the work done by the braking force will be same. Given that braking force on the two vehicles is same, the distance covered by them is same.

Power:

Power is the time rate of doing work.

Accordingly, the power P developed by a force F which does an amount of work W is

= F.v

Suppose a man rises walking on the top of a hill and another man goes riding on a motor bike. Both have done the same amount of work, but the second man has used more power, because he would have done the same amount of work faster.