A playground merry-go-round has a disk-shaped platform that rotates with negligible friction about a vertical axis. The disk has a mass of 200 kg and...

A playground merry-go-round has a disk-shaped platform that rotates with negligible friction about a vertical axis. The disk has a mass of 200 kg and a radius of 2.0 m. A 42- kg child rides at the center of the merry-go-round while a playmate sets it turning at 0.10rpm. If the child then walks along a radius to the outer edge of the disk, how fast will the disk be turning (in rpm)?