A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of
The following statements about the bounce are correct? (There could be more than one correct
Choice.)
A) The ball had the same momentum just before and just after the bounce.
B) The ball's momentum was conserved during the bounce.
C) The magnitude of the ball's momentum was the same just before and just after the bounce.
D) None of the above statements are correct.

Question

Quizplus · Accepted Answer

The magnitude of the ball's momentum was the same just before and just after the bounce because momentum is mass times velocity, and although the direction of the velocity changes (from downward to upward), the speed (and thus the magnitude of the velocity) and the mass of the ball remain the same. Choices A and B are incorrect because the direction of the momentum changes, which means the momentum just before and just after the bounce are not the same, indicating that the momentum was not conserved in its original direction.

A Very Elastic Rubber Ball Is Dropped from a Certain