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 magnitude of the ball's momentum was the same just before and just after the bounce.
C)The ball's momentum was conserved during the bounce.
D)None of the above statements are correct.

Question

Quizplus · Accepted Answer

CThe magnitude of the ball's momentum is the same just before and just after the bounce because momentum is mass times velocity, and only the direction of the velocity changes, not its magnitude. Momentum is conserved during the bounce because the change in momentum (which involves the ball going from downward to upward motion) is equal and opposite, assuming no external forces act on the system other than the normal force from the floor, which is an internal force for the system consisting of the ball and the Earth.

A Very Elastic Rubber Ball Is Dropped from a Certain