Problem 12. A pendulum, consisting of a mass less string of length L and a small sphere of mass m,swings in a vertical plane. The string hits a peg located

a distance d below the point of suspension.You want to release the pendulum from rest from the horizontal position and you want it to be able to swing in a complete circle centered on the peg. Show that the minimum value of d that makes this possible is 3L/5.