Question

In the situation illustrated below, (1) Car A is given a push. Almost immediately after the push, Car A collides with Car B, which is stationary. This results in (2) Car A stopping, and Car B moving away from the collision with approximately the same speed Car A had right before the collision. Then Car B gradually slows down, and sometime later, (3) it comes to a stop. Which explanation below best describes the changes in the motion of Car B in terms of energy? (Note: KE=kinetic energy, TE=thermal energy.)

Answer 1

The best explanation for the changes in the motion of Car B in terms of energy is:

1. Initially, Car B is stationary, so it has no kinetic energy (KE).
2. After the collision, Car B moves with approximately the same speed as Car A had before the collision. Thus, Car B gains kinetic energy (KE) from Car A during the collision.
3. As Car B moves and gradually slows down, some of its kinetic energy (KE) is transformed into thermal energy (TE) due to friction between the car wheels and the road. This conversion of KE to TE continues until Car B comes to a stop, at which point it has no kinetic energy left.