A pendulum, comprising a string length L and a small sphere, swings in the vertical plane. The string hits a peg located a distance d below the point of suspension. Show (A) that if the sphere is released from a height below that of the the peh, it will return to this height after striking the peg and (B) that if the pendulum is released from the horizontal position and is to swing in a complete circle centred on the peg, then the minimum value of d must be 3L/5. These questions just kill me. There's always one on the assignment and it's always the one question I can't do. :grumpy: Any help would be greatly appreciated.