Question

A ball is dropped from height 10 m. Ball is embedded in sand 1 m and stops

• A. only momentum remains conserved.
• B. only kinetic energy remains conserved.
• C. both momentum and kinetic energy are conserved.
• D. Neither kinetic energy nor momentum is conserved.

Answer 1

The correct option is D

Neither kinetic energy nor momentum is conserved.

1. Law conservation of momentum states that the momentum of a system is constant if no external forces are acting on the system.
2. When the ball is dropped, then gravitational force and frictional force (due to sand) acts on the ball. These are the external forces. So, momentum will not be conserved.
3. Velocity of the ball changes due to gravitational force and frictional force. So, kinetic energy also changes. So, kinetic energy is also not conserved.
4. Hence, neither kinetic energy nor momentum is conserved.

Thus, option (d) is correct.