Chapter 9, Problem 1OQ

To determine

Rank of the following cases.

Answer to Problem 1OQ

The rank from largest to smallest is $b>e>a=d>c$ .

Explanation of Solution

When the lab partner  throws a heavy frisbee. It comes with high momentum and collides with the hand. At the moment frisbee is held in hand and thrown back, this collision of frisbee with hand leads to transfer of momentum of frisbee  to the hand . Increasing the velocity of hand.

Hence velocity is maximum when hand catches the ball and throws back.

While the velocity is minimum when frisbee just touches the fingers and hand does not stop them as no momentum transfer takes place.

Conclusion:

Case (a):

As soon as hand catches the frisbee and holds it , both mass of frisbee and body act as single unit and which implies larger mass. As momentum should be conserved so initial momentum is transferred to large mass with less velocity. Here less velocity is acquired.

Case (b):

Here velocity is largest. At the moment during collision of hand and frisbee, momentum gets transferred to hand which increases the velocity of hand. Thus, the velocity is largest.

Case (c):

Frisby just bobbles the hand and get away from the hand. Here velocity of hand will be minimum as no transfer of momentum takes place.

Case (d):

Here the hand throws the ball vertically upward , body experiences normal force from ice which stops the body from falling.

Case (e):

As the hand holds the Frisbee and keep it down to rest, at this moment some momentum is gained by the hand from Frisbee which is not too large in magnitude but is greater than the case when Frisbee is just held into hand.

Thus, the rank from largest to smallest is $b>e>a=d>c$.