Question

A ball hits the floor and rebounds after an elastic collision. In this case:

• A. the momentum of the ball just after the collision is same as that just before the collision.
• B. the kinetic energy of the ball remains same during collision.
• C. the total momentum of the ball and the earth is conserved.
• D. the total energy of the ball and the earth remains the same.

Answer 1

Answer: (C), (D)

The correct options are
C the total momentum of the ball and the earth is conserved.
D the total energy of the ball and the earth remains the same.

Since the velocity before and after the collision change hence momentum of the ball will change. So (a) is not true.

Since the collision is inelastic a part of the mechanical energy is lost hence (b) is not true.

Taking earth and the ball as a system there is no external force on the system. Hence the total momentum of the ball and the earth is conserved. So (c) is true.

From the conservation principle of the energy, the total energy of the ball and the earth remains the same. Hence (d) is true.