Problem 74P

A student on a piano stool rotates freely with an angular speed of 2.95 rev/s. The student holds a 1.25-kg mass in the 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 5.43 kg -m2, a value that remains constant. (a) As the student pulls his arms inward, his angular speed increases to 3.54 rcv/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 energies of the system.

Solution 74P

Step 1 of 5

Here our objective is to first determine the final distance of the masses from the axis of rotation when the student pulls his arms inward and then calculate the initial and final kinetic energies of the system.