A student on a piano stool rotates freely with an angular speed of 2.95 rad/s . The student holds a 1.35 kg mass in each outstretched arm, 0.739 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 5.13 kg m^2, a value that remains constant. As the student pulls his arms inward, his angular speed increases to 3.51 rad/s. Having found that the new radius of rotation for the weights is .395 m, what is the initial and final kinetic energy for the system?

Question

A student on a piano stool rotates freely with an angular speed of 2.95 rad/s . The student holds a 1.35 kg  mass in each outstretched arm, 0.739 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 5.13 kg m^2, a value that remains constant. As the student pulls his arms inward, his angular speed increases to 3.51 rad/s. Having found that the new radius of rotation for the weights is .395 m, what is the initial and final kinetic energy for the system?