## College Physics (7th Edition)

(d) The change in momentum of the ball is $2mv$.
Initial momentum of the ball, $\vec{p_i}=m\vec v$ After the ball hits the wall and bounces back, its velocity is $-v$. Thus, final momentum, $\vec{p_f}=m(-\vec v)$. Change in momentum, $\vec{p_i}-\vec{p_f}=2m\vec v$.