Question

A cricket ball of mass 0.4 kg moving with vilocety of 72 km/ h is brouht to rest by player waht is magnitude of averge force exerted by the player

Answer 1

Mass of the cricket ball = 0.4 kg

Initial velocity u with which the ball is moving= 72 km per hour= 72 km/h= 20 m/s

Final Velocity v of the ball when stopped= 0 m/s

Change in momentum= final momentum - initial momentum = 0.4 kg× 0 m/s - 0.4 kg× 20 m/s = (0 - 8) kg×m/s= impulse = F×time.

Impulse of the ball= 8 kg-m/s = F× t.

Since in the question it is not stated in how much time the ball is brought to rest, we can not calculate the average force. However, once we know that the force which needs to be applied to stop the ball multiplied by the time in which the ball is stopped= 8 N-s.