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)` above ground. Consider the ground to be perfectly rigid and neglect air friction. In the time interval from `t = 0` to `t = t_(0)`, pick up the correct statements.

Options

A. Work done by gravity on ball is `mg (h_(1) - h_(2))`
B. Work done by gravity on ball is `mg (h_(2) - h_(1))`
C. Average acceleration of the ball is zero.
D. Net work done on the ball by all forces except gravity is `mg (h_(2) - h_(1))`

Answer

A, C, D

Explanation

From the figure-`1` work done by gravity from ` t = 0` to `t =- t_(0)` is `W = mg(h_(1) - h_(2))`

Since initial and final velocity of ball is zero its average acceleration will be zero
Since net work done is zero from time interval `t = 0` to `t = t_(0)`
Hence work done by forces except gravity is `mg(h_(2) - h_(1))`