Question

Why cricketer while taking a catch moves his hand back wards

Answer 1

while catching a fast moving cricket ball , a fielder in the ground gradually pulls his hand backwards with the moving ball, In doing so, the fielder increases the time during which the high velocity of the moving ball descrease to zero. thus, the accleration of the ball is descreased and therefore the impact of catching the fast moving ball is also reduced.

if the ball stopped suddenly then it's high velocity is descreases to zero in a very short interval of time.

thus, the rate of change of momentum of the ball will be large. therefore, a large force would have to be applied for holding the catch that may hurt the palm of the fielder.

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BEST OF LUCK :-)

#akashmandal.

Answer 2

A cricket player moves his hands backwards on catching a fast cricket ball to prevent injury to the hands.
Reason:
--->A fast moving cricket ball has a larger momentum.The momentum of the ball has to be reduced to zero in order to catch .
---->When cricket player moves his hands back ,  the time taken  to reduce the momentum of the ball to zero is increased.
----> Due to more  time taken to stop the ball, the rate of change of momentum of ball is reduced and hence a small force is exerted on the hands of players. So, the hands of player do not get hurt.
--->If the cricket player stops the fast moving ball suddenly, then large momentum of the ball will be reduced to zero in a very short time , due to which the rate of change of momentum of ball will very large which will exert a large impact force on player's hand causing the injury to his hands.

Conclusion:
To prevent injury to his hands, always a  cricket player moves his hands backwards on catching a fast cricket ball