Question

Select correct options.

• A. In hitting or kicking a ball we decrease the time of contact so that large force acts on the ball producing greater acceleration.
• B. In catching a ball by drawing hands backwards, increases the time of contact and so, lesser force acts on hands and hands are saved from getting hurt.
• C. An athlete is advised to come to stop slowly after finishing a fast race. So that time of stop increases and hence force experienced by him decreases.
• D. None of these

Answer 1

Answer: (A), (B), (C)

The correct options are
A In hitting or kicking a ball we decrease the time of contact so that large force acts on the ball producing greater acceleration.
B In catching a ball by drawing hands backwards, increases the time of contact and so, lesser force acts on hands and hands are saved from getting hurt.
C An athlete is advised to come to stop slowly after finishing a fast race. So that time of stop increases and hence force experienced by him decreases.

Change in momentum $=F.\delta t$ $=$ Impulse

When acceleration or change in moment required is more with same force available, then contact time is reduced.

But, when u have to catch a ball then change in momentum is constant but force felt can be reduced by increasing the contact time.

Same in case of the athlete coming to rest change in momentum is same but if he stops slowly, time of contact increases which reduces the force exerted by the earth on the athlete.