Final answer:
The rubber ball has potential energy due to its position near the edge of the bookshelf. When it bounces off the floor, it loses some kinetic energy due to inelastic collisions, causing it to reach only 90% of its original height.
Step-by-step explanation:
The rubber ball near the edge of the bookshelf has no kinetic energy because it is motionless. However, it does have potential energy. Potential energy is the energy that an object possesses due to its position or state. In this case, the potential energy of the rubber ball is due to gravity pulling it downwards. When the ball is dropped and bounces off the floor, it loses some of its kinetic energy due to inelastic collisions.
Inelastic collisions involve the loss of kinetic energy as the objects collide and deform, like the rubber ball compressing and losing some energy during the bounce. As a result, the ball only reaches 90% of its original height.