A sphere rolls down the loop-the-loop track shown in Figure P9.21, starting from rest at...

A sphere rolls down the loop-the-loop track shown in Figure P9.21, starting from rest at a height h above the bottom. The ball travels around the inside of the circular portion of the track (radius r = 5.0 m). It is found that the ball is just barely able to travel around the inside of the track without losing contact at the top. Find h.