Question

A hockey ball of mass 0.2kg traveling at 10m/s is struck by a hockey stick so as to return it along its original path with a velocity at 2m/s. calculate the change in momentum of the hockey ball?​

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. momentum = Final momentum - Initial momentum = - 1Ns - 2Ns = - 3N s. (Minus sign denotes change in momentum in the direction opposite to the direction of initial momentum of the ball.

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Answer 2

Answer :-

-0.4kg m/s

Explanation :-

Given :

• Mass of the hockey ball,m => 0.2kg

• Initial velocity of the hockey ball,u => 10m/s

• Final velocity of the hockey ball,v => -2m/s

Note => we have taken  final velocity as negative because it moved in  opposite direction.

To Find :

• Change in momentum of the hockey ball = ?

Solution :

We know,

$\sf{}Change\ in\ momentum= m \times(v-u)$

Put their values and solve it.

$\sf{}\implies0.2 \times(-2-10)$

$\sf{}\implies 0.2 \times-12$

$\sf{}\sf{}\therefore -0.4kg\ m/s$

Therefore,change in momentum is equal to -0.4kg m/s