Q. A body falling from a height of $10m$ rebounds from hard floor. If it loses 20% energy in the impact, then coefficient of restitution is
A) 0.89
B) 0.56
C) 0.23
D) 0.18
Explanation
(a) As 20% energy lost in collision therefore
$mgh_{2} = 80\%\ of\ mgh_{1} \Rightarrow \frac{h_{2}}{h_{1}} = 0.8$
But $e = \sqrt{\frac{h_{2}}{h_{1}}} = \sqrt{0.8} = 0.89$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.