Question

A heavy steel ball of mass greater than 1 kg moving with a speed of 2m/ s collides head on with a stationary ping pong ball of mass less than 0.1 g. The collision is elastic. After the collision the ping pong ball moves approximately with a speed

• A. $2m/s$
• B. $4m/s$
• C. $2\times {10}^{4}m/s$
• D. $2\times {10}^{3}m/s$

Answer 1

Answer: (B)

$4m/s$

Since the body is much heavy these won't be much change in velocity
& $e=1$

i.e., $\frac{v-2}{0-2}=-1$

$\Rightarrow v=4m/s$