A figure skater has her arms extended outwards at her sides, while spinning at a rate of 1.2 rev/s. If she pulls her arms close to her body, the rotation speed will increase to 1.8 rev/s.
(a) Why does the rotation speed increase?
(b) Express her final moment of inertia in terms of her initial moment of inertia.

• A. (a) The skater's angular speed increases due to a decrease in the moment of inertia; (b) The moment of inertia has decreased by a factor of 0.67
• B. (a) The skater's angular speed increases due to a decrease in the moment of inertia; (b) The moment of inertia has decreased by a factor of 0.57
• C. (a) The skater's angular speed increases due to an increase in the moment of inertia; (b) The moment of inertia has increased by a factor of 0.67
• D. (a) The skater's angular speed increases due to an increase in the moment of inertia; (b) The rotational speed has increased by a factor of 0.57

Answer: (A)