Question

A particle of mass $m$ collides head-on with another stationary particle of mass $M$ such that the second particle starts moving and the first particle comes to rest after the collision. Which of the following conditions is valid if the coefficient of restitution is $e$ ?

• A. $e=0$
• B. $e=\frac{m}{M}\leq 1$
• C. $e=\frac{m}{M}\geq 1$
• D. $e=\frac{M}{m}\leq 1$

Answer 1

Answer: (B)

The collision is not perfectly elastic or inelastic since when one is at rest the other is in motion with different velocities
$mu=Mv$
$\Rightarrow \, \, \, \frac{m}{M}=\frac{v}{u}$
But $e=\frac{v}{u}\leq 1$
$e=\frac{m}{M}\leq 1$