Explain how a figure skater controls angular velocity when performing a multiple spin about the longitudinal axis.

Angular velocity is defined as the rate of change of the angular position of a rotating body. Angular momentum is spin and depends upon the moment of inertia and angular velocity. Moment of inertia and angular velocity are inversely proportional thus as one increases, the other decreases. Therefore, in order to control angular velocity, an ice skater must manipulate the moment of inertia as angular momentum is conserved in the air and on the ice as it is a friction free surface.At the start of a multiple spin, the ice skater brings their arms wide and lifts their leg out to the side. This increases the distribution of mass from the axis therefore the moment of inertia increases leading in a decrease of angular velocity so rotation is slow and the ice skater can prepare themselves for the take-off while balanced. As the ice skater takes off and performs the spin, she wants to gain angular velocity to complete more spins in the air. Thus, she pulls her arms and legs in quickly by the sides of the body to decrease the distribution of mass from the axis which reduces moment of inertia and increases angular velocity. Finally as the skater lands, to gain control she opens her body out lifting the leg out to the side and bringing her arms out in order to increase the distance of these body parts to the axis of rotation so that moment of inertia decreases. This leads to a reduced angular velocity so rotation is slow, and she can control the landing and not lose balance.