Question

A tennis ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. What fraction of energy is lost in the impact?

• A. $\frac{1}{4}$
• B. $\frac{1}{8}$
• C. $\frac{1}{2}$
• D. $\frac{1}{16}$

Answer 1

Answer: (A)

$\frac{1}{4}$

We know that the potential energy is dependent on the height. Let us consider the tennis ball dropped from height $H$ has P.E of $mgH$.

Then $mgh$ will be the potential energy while the ball rebounds.

Here,$H=2m$ and $h=1.5m$

Then, loss of energy $=\frac{mg(H-h)}{mgH}$

$=\frac{H-h}{H}=\frac{2-1.5}{2}=\frac{1}{4}$

Therefore, fraction of energy lost in the impact $=\frac{1}{4}$