Question

applications of second law of motion by Newton

Answer 1

1-A fast moving ball has a large momentum.In stopping this ball its momentum has to be reduced to zero.Now when a cricket player moves back his hands on catching the fast ball,then the time taken to reduce the momentum to zero is increased.Due to more time taken to stop the ball,the rate of change of momentum is decreased and hence a small force is exerted on the hands of player.So his hands do not hurt.

2-A karate player is able to break the slab of ice with the single fast blow because a karate player strikes the slab with his hand very very fast.In doing so,the large momentum of the fast moving hand is reduced to zero in a very short time.This exerts a very large force on the slab which is sufficient to break them apart.