Question

A ball is dropped from height $10\, m$. It is embedded in sand $1m$ metre and stops.

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

Answer 1

Answer: (D)

Neither momentum nor kinetic energy is conserved.

Answer 2

For the Ball: weight of the ball and resistance due to sand are external forces. Hence, momentum is not conserved unless external force is zero.