11.3 Exercise 15

A bug of mass 0.020 kg is at rest on the edge of a solid cylindrical disk $\left(M = 0.10 \text{kg}, R = 0.10 \text{m}\right)$ rotating in a horizontal plane around the vertical axis through its center. The disk is rotating at 10.0 rad/s. The bug crawls to the center of the disk. (a) What is the new angular velocity of the disk? (b) What is the change in the kinetic energy of the system? (c) If the bug crawls back to the outer edge of the disk, what is the angular velocity of the disk then? (d) What is the new kinetic energy of the system? (e) What is the cause of the increase and decrease of kinetic energy?