8.4 Exercise 5

Two cars (A and B) of equal mass have an elastic collision. Prior to the collision, car A is moving at 15 m/s in the +x-direction, and car B is moving at 10 m/s in the –x-direction. Assuming that both cars continue moving along the x-axis after the collision, what will be the velocity of car A after the collision?

1. same as the original 15 m/s speed, opposite direction
2. equal to car B’s velocity prior to the collision
3. equal to the average of the two velocities, in its original direction
4. equal to the average of the two velocities, in the opposite direction