Skater 1

A figure skater is spinning on ice with their arms extended. When they pull in their arms, what happens to their moment of inertia? Assume friction and drag are negligible.

A) Increases

B) Decreases

C) Stays the same

D) Can't tell, not enough information

Solution: Moment of inertia depends upon the mass and how far it is from the axis of rotation. The moment of inertia must decrease since the distance to the axis of rotation decreases for some of the mass.