A child stands at the center of the turn-table with his two arms outstretched, rotating with an angular speed of 40 rpm. What will be the angular speed of the child if he folds his hand back and thereby reduced his moment of inertia to 2/3 times the initial value? Also, find the ratio of the new kinetic energy of rotation to the initial kinetic energy of the rotation. (No friction anywhere)
1
100 rpm, 2.5
2
60 rpm, 1.5
3
150 rpm, 2.3
4
100 rpm, 0