8.4 Exercise 7

A rubber ball is dropped from rest at a fixed height. It bounces off a hard floor and rebounds upward, but it only reaches 90% of its original fixed height. What is the best way to explain the loss of kinetic energy of the ball during the collision?

1. Energy was required to deform the ball’s shape during the collision with the floor.
2. Energy was lost due to work done by the ball pushing on the floor during the collision.
3. Energy was lost due to friction between the ball and the floor.
4. Energy was lost due to the work done by gravity during the motion.