Chapter 9, Problem 40A

(a)

To determine

Change in skater’s angular momentum.

Explanation of Solution

Introduction:

Angular momentum is the product of moment of inertia and angular velocity. Torque can be described as rate of change of angular momentum.

Angular momentum of body spinning depends on external torque applied. So, skater must apply the external torque to change the angular momentum of it.

Conclusion:

External torque must be applied to change the skater’s angular momentum.

(b)

To determine

The change in angular velocity of the skater without changing the angular momentum.

Explanation of Solution

Introduction:

Angular velocity is rate of change of angular displacement with respect to time.Angular velocity is a vector quantity.

Angular velocity of skater depends on moment of inertia. So angular velocity of skater can be changed by changing the moment of inertia.