Question

Raju dropped a rubber ball of mass m from a height h to the ground. He observed that the ball rebounds vertically and along the same line to a height h₁, which is less than h.

1. Is it an elastic or inelastic collision?

2. Find the velocity with which it strikes the ground?

3. If it is replaced by a solid aluminium ball, then what happens to the height of rebound?

4. If the rubber ball is allowed to fall on a spring placed on the ground then what change will Raju notice in the height of rebound?

Answer 1

1. Inelastic collision.

2. The velocity with which ball strikes the ground,

v² = u² + 2as

v² = 0 + 2g × h

v = \(\sqrt {2gh}\).

3. Height of rebound decreases.

4. Height of rebound depends on the state of potential energy stored in the spring. If ball falls on a compressed spring, the height of rebound increases due to potential energy given by the spring to bail.