Explain the following situations by relating force and
time
*At the time of catching a cricket ball, the time of
catching is extended by moving the hand backward
with the ball.
*During a pole vault jump, the impact is reduced
by falling on a foam bed.
*Hay or sponges are used while packing glasswares.
This helps to avoid breaking of glasswares due to
collision.
*Karate experts move their hands with great speed to chop strong bricks.
Answers
Answer:
a.
While catching a fast moving cricket ball, a fielder in the ground gradually pulls his hand backward with the moving ball, In doing so, the fielder increases the time during which the high velocity of the moving ball decrease to zero. Thus, the acceleration of the ball is decreased and therefore the impact of catching the fast moving ball is also reduced.
If the ball stopped suddenly then its high velocity is decreased 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.
b.When the change in momentum is a constant, the force acting on a body will be inversely proportional to the time taken. As time increases, the force acting decreases, and as time decreases, the force acting increases. On a foam bed, the body takes some time toto rest as the bed is pressed. So, the impact is reduced.
c.When the change in momentum is a constant, the force acting on a body will be inversely proportional to the time taken. As time increases, the force acting decreases, and as time decreases, the force acting increases. In the case of the glass, the hay prevents any impact on the glass and stops the sudden change in the momentum of the glass material.
d.When the change in momentum is a constant, the force acting on a body will be inversely proportional to the time taken. As time increases, the force acting decreases and as time decreases, the force acting increases.
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