Question

A ball hits the floor and rebounds after an inelastic collision. In this case
A. the momentum of he 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 energy of the ball and the earth is conserved

Answer 1

Correct Answer - C::D
(c,d) (a) is wrong because the momentum of ball changes
in magnitude as well as direction.
(b) is wrong because on collision, some mechanical
energy is converted into heat, sound energy.
(c) is correct because for earth +ball system the impact
force is an internal force.
(d) is correct.