An ice skater spins about a vertical axis at an angular speed of 15 rad/sec when her arms are outstretched. She then quickly pulls her arms into her sides in a very small time interval so that the frictional forces due to ice are negligible. Her initial moment of inertia about the axis of rotation is 1.72 kg m2 and her final moment of inertia is 0.61 kg m2. What is the change in her angular speed? What is the change in her kinetic energy? Explain this change in kinetic energy.