## Kinetic Energy and Momentum Conceptual Question

The two toy cars shown in the figure, with masses as given in the figure, are ready to race. Both cars begin from rest. For each question, state whether the correct answer is car A, car B, or whether the two cars have equal values for the parameter in question.

For the next three parts assume that the cars’ motors supply the same force to each car over the course of a 1.0-meter race.

**A) Which car crosses the finish line 1.0 m away first?**

**B) Which car has the larger kinetic energy when it crosses the finish line 1.0 m away?**

**C) Which car has a larger momentum when it crosses the finish line 1.0 m away?**

**D) Which car has traveled farther after 10 s?**

**E) After 10 s which car has a larger kinetic energy?**

**F) After 10 s which car has a larger momentum?**

## Answer ( 1 )

The two toy cars shown in the figure, with masses as given in the figure, are ready to race. Both cars begin from rest. For each question, state whether the correct answer is car A, car B, or whether the two cars have equal values for the parameter in question.

For the next three parts assume that the cars’ motors supply the same force to each car over the course of a 1.0-meter race.

A) Which car crosses the finish line 1.0 m away first?=> Car B wins

B) Which car has the larger kinetic energy when it crosses the finish line 1.0 m away?=> Both cars have the same kinetic energy

C) Which car has a larger momentum when it crosses the finish line 1.0 m away?=> Car A

D) Which car has traveled farther after 10 s?=> Car B

E) After 10 s which car has a larger kinetic energy?=> Car B

F) After 10 s which car has a larger momentum?=> Both cars have the same momentum.