Question

Question 13
A hockey ball of mass 200 g travelling at $10m{s}^{-1}$ is struck by a hockey stick so as to return it along its original path with a velocity at $5m{s}^{-1}$. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.

Answer 1

Mass of the hockey ball, m = 200 g = 0.2 kg
Hockey ball travels with velocity, $v_1$ = 10 $m{s}^{-1}$
Initial momentum $=m{v}_1$
Hockey ball travels in the opposite direction with velocity, $v_2$ = $-5m{s}^{-1}$
Final momentum $=m{v}_2$
Change in momentum $=m{v}_1-m{v}_2=0.2[10-(-5\left)\right]=0.2\left(15\right)=3kgm{s}^{-1}$
Hence, the change in momentum of the hockey ball is $3kgm{s}^{-1}.$