Question

A hockey ball of mass 200 g bits on a hockey stick with a velocity
10 m/s. Calculate the change in momentum if the ball bounces back on
the same path with the same speed,
​

Answer 1

Mass of the hockey ball, m = 200 g = 0.2 kg

Hockey ball travels with velocity, v1 = 10 m/s

Initial momentum = mv1

Hockey ball travels in the opposite direction with velocity, v2 = ˆ’5 m/s

Final momentum = mv2

Change in momentum = mv1 ˆ’ mv2 = 0.2 [10 ˆ’ (ˆ’5)] = 0.2 (15) = 3 kg m sˆ’1

Hence, the change in momentum of the hockey ball is 3 kg m sˆ’1.

Answer 2

Answer :-

m = 200g = 200/1000 = 0.2 kg

Initial momentum = mu

= 0.2 × 10 = 2 kg m/s

Final momentum = mv

= 0.2 × 70 = 2 kgm/s

change in momentum = mv – mv = – 2 – 2

= -4 kg m/s