# A tennis ball dropped from height of $2m$ rebounds only $1.5 m,$ after hitting the ground , What fraction of energy is lost in the impact

$(a)\;\frac{1}{2} \quad (b)\;\frac{1}{4}\quad (c)\; \frac{1}{8} \quad (d)\;\frac{1}{16}$

Fraction of energy lost $=\large\frac{\Delta E}{E}$
$\large\frac{mg(h-h')}{mgh}=\frac{h-h'}{h}$
$=\large\frac{2-1.5}{2}=\frac{1}{4}$
Hence b is the correct answer.

edited Feb 17, 2014 by meena.p