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

Answer: (D)

-2mu

Answer 2

The situation is as shown in the figure.

$p_{initial} = mu,p_{final} = - mu$

Impulse imparted to the ball = Change in momentum

$= p_{final} - p_{inital} = - mu - mu = - 2mu$