Question

A ball is thrown with a velocity of $6m/s$ vertically from a height $H=3.2m$ above a horizontal floor. If it rebounds back to same height then coefficient of restitution $e$ is $[9=10m/s^2]$

• A. $0.5$
• B. $0.6$
• C. $0.7$
• D. $0.8$

Answer 1

The correct option is D $0.8$

$\begin{array}{c}{v}_1=\sqrt{6^2+2\times 10\times 3.2}=10m/s\\ v_2=\sqrt{2\times 10\times 3.2}=8m/s\\ \therefore e=\frac{v_2}{v_1}=\frac{8}{10}=0.8\\ Ans.\left(D\right)\end{array}$