Question

A small ball of mass $m$ is released from rest at a height $h_1$, above ground at time $t=0$. At time $t=t_0$ the ball again comes to rest at a height $h_2$. Consider the ground to be perfectly rigid and neglect friction, In the time interval from $t=0\text{to}t=t_0$. Pick up the Incorrect statement

• A. Work done by gravity on ball is $mg(h_1-h_2)$
• B. Work done by ground on ball for duration of contact is $mg(h_2-h_1)$
• C. Average acceleration of the ball is zero
• D. Net work done on the ball by air forces except gravity is $\mathrm{mg}(h_2-h_1)$

Answer 1

Answer: (A), (C)

The correct options are
A Work done by gravity on ball is $mg(h_1-h_2)$
C Average acceleration of the ball is zero