Question

i) A hockey ball of mass 100 g travelling at 20 ms' is struck, by a hockey stick so as to return it
along its original path with a velocity at 10 ms'. Calculate the change of momentum occurred in the
motion of the hockey ball by the force applied by the hockey stick.
ii) If action is always equal to the reaction, explain how a horse can pulls a cart?​

Answer 1

Answer:

Explanation:

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.

Solution

Given, mass of the ball (m) = 200g

Initial velocity of the ball (u) = 10 m/s

Final velocity of the ball (v) = – 5m/s

Initial momentum of the ball = mu = 200g × 10 ms-1 = 2000 g.m.s-1

Final momentum of the ball = mv = 200g  × –5 ms-1 = –1000 g.m.s-1

Therefore, the change in momentum (mv – mu) = –1000 g.m.s-1 – 2000 g.m.s-1 = –3000 g.m.s-1

This implies that the momentum of the ball reduces by 1000 g.m.s-1 after being struck by the hockey stick.