Chapter 4, Problem 70A

To determine

To Explain:The player moves hand in the direction of motion of ball.

Explanation of Solution

Introduction:

From Newton’s second law of motion:

Force = rate of change in momentum

  $F=\frac{m\Delta v}{\Delta t}=ma$

When a fast-moving ball is coming towards player, he should move the hand in the direction of the motion of the ball. This is because, it will increase the time in which the momentum of ball changes, i.e., the high velocity comes to rest in more time which will decrease the acceleration and hence, less force would act on the hand reducing the chances of injury. If the hand would be moved towards the ball, the acceleration would be high and hand would get injured because of high impact force.

Conclusion:

The hand should be moved in the direction of the motion of the force to reduce the chances of injury.