A student on a piano stool rotates freely with an angular speed of 3.30 rev/s. The student holds a 1.38-kg mass in each outstretched arm, 0.759 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 4.78 kg · m2, a value that remains constant.
(a) As the student pulls his arms inward, his angular speed increases to 3.54 rev/s. How far are the masses from the axis of rotation at this time, considering the masses to be points?
(b) Calculate the initial and final kinetic energy of the system.