Question

A ball of mass $m$ moving with uniform speed, collides elastically with another stationary ball. The incident ball will lose maximum kinetic energy, when the mass of the stationary ball is,

• A. $m$
• B. $2m$
• C. $4m$
• D. infinity

Answer 1

The correct option is A $m$


Collision is perfectly elastic.
$\Rightarrow$ Maximum possible loss of $K.E.$ of ball $\left(1\right)$ will be $=\frac{1}{2}m{v}^2$; when the first ball comes to rest after collision.
$\Rightarrow u_1=u,u_2=0,v_1=0,v_2=u$

According to conservation of momentum principle,
$mu+0=0+m_{2}u$
$\Rightarrow m_2=m$

Hence, $\left(A\right)$ is the correct answer.