Question

A ball of mass $m$ strikes a rigid wall with speed $u$ and rebounds with the same speed. The impulse imparted to the ball by the wall is

• A. $2mu$
• B. $mu$
• C. zero
• D. $-2mu$

Answer 1

The correct option is D $-2mu$


The situation is as shown in the figure.
$p_{\text{initial}}=mu,p_{\text{final}}=-mu$
Impulse imparted to the ball = change in momentum $=p_{\text{final}}-p_{\text{intial}}$
$=-mu-mu=-2mu$