Question

A particle of mass $m$ is moving horizontally with a constant velocity $\nu$ towards a rigid wall that is moving in opposite direction with a constant speed $u$. Assuming elastic impact between the particle and wall, the work done by the wall in reflecting the particle is equal to

• A. $\left(1/2\right)m(u+\nu {)}^2$
• B. $\left(1/2\right)m(u+\nu )$
• C. $\left(1/2\right)mn\nu$
• D. None of these

Answer 1

Answer: (D)

None of these

$e=0$

$\Rightarrow v^{\prime }-u=0$

$\Rightarrow v^{\prime }=u$

$\therefore$ Change in KE$=0.$

Hence, the answer is none of these.