Question

2 identical trains travel with the same speed toward the station. TRAIN A immediately begins to slow down and gently comes to a stop. TRAIN B continues at the same speed until the last moment and slams on the breaks, suddenly stopping. Which train's breaks do more work?

Answer 1

The work done in both cases is the same. The work energy theorem states that the work done on the train by the brakes equals the change in the kinetic energy of the train. Since both trains start at the same velocity and come to a rest the change in kinetic energy is the same for both so the work done is the same even though the time taken for this work is much different.