Question

A ball hits the floor and rebound after inelastic collision. In this case :

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

Answer 1

The correct option is C the total momentum of the ball and the earth is conserved

Momentum of the system changes only due to external force (OR impulse).

When a ball hits the floor and gets rebound, then no external force (Impulse) acts on the ball as well as the floor, thus total momentum of the "ball + earth" system remains conserved.

Also some of the mechanical energy of the ball is always lost in an inelastic collision due to its deformation, hence it cannot remain conserved in this collision.