Question

A 1.0 kg ball drops vertically int a floor from a height of 25 cm. It rebounds to a height of 4 cm. The coefficient of restitution for the collision is-

• A. 0.16
• B. 0.32
• C. 0.4
• D. 0.56

Answer 1

Answer: (C)

0.4

Velocity just after collision
$u=\sqrt{2gh}$
$u=\sqrt{2\times 10\times \frac{25}{100}}$
$u=\sqrt{5}m/s$
Velocity after collision $=v$
$v=\sqrt{2gh}$
$=\sqrt{2\times \frac{10\times 4}{100}}$
$v=\sqrt{10.8}$
$e=\frac{v}{u}=\frac{\sqrt{10.8}}{\sqrt{5}}=0.4$