Question

A ball falls from a height of 10m on to a horizontal plane. If the coefficient of restitution is 0.4 the velocity with which it rebounds from the plane after second collision is

• A. $2.24m{s}^{-1}$
• B. $5.6m{s}^{-1}$
• C. $2.8m{s}^{-1}$
• D. $0.9m{s}^{-1}$

Answer 1

The correct option is A $2.24m{s}^{-1}$

$e=\sqrt{\frac{h_2}{h_1}}$

$\Rightarrow \sqrt{h_2}=e\sqrt{10}$

$\sqrt{h_3}=e^2\sqrt{10}$

$v=e^{2}10\sqrt{2}=\sqrt{2g{h}_3}$

$=1.6\sqrt{2}=2.24m/s$