12
Question Question 12
A hockey ball of mass 200 g travelling at 10 ms-1 is struck by a hockey stick so as to return it along its original path with a velocity at 5 ms-1. Calculate the magnitude of change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.
Given,
Mass (m) = 200 g
Initial velocity (u) = 10 ms-1
Final velocity (v) = -5 ms-1
Initial momentum of the ball = mu = 200 × 10 = 2000 gms-1
Final momentum of the ball = mv = 200 × -5 = -1000 gms-1
∴ The change in momentum (mv - mu) = -1000 - 2000 = -3000 gms-1
Convert gms-1 to kgms-1 :
1000 gms-1 = 1 kgms-1
So, 3000 gms-1 = = -3 kgms-1
Hence, momentum of the ball reduces by 3 kgms-1 after being struck by the hockey stick.