A figure skater begins a spin with arms and one leg fully extended. While spinning on friction-free ice, the skater pulls the arms and leg close to the body, reducing the moment of inertia of the skater–body system by 40 percent. No external torques act during the maneuver.
(a) Describe qualitatively how the skater’s angular speed changes as the arms and leg are pulled in.
(b) State whether the skater’s rotational kinetic energy increases, decreases, or remains the same. Provide a clear explanation that accounts for both angular momentum conservation and energy considerations.
(c) Identify the forces that do work, if any, during the maneuver and explain how your answer in part (b) is consistent with this identification.