assume that the center of mass of a girl crouching in a light swing has been raised to 1.2m. the girl weighs 400n and her center of mass is 3.7m from the pivot of the swing while she is in the crouched position. the swing is released from rest and at the bottom of the arc the girl stands up instantaneously, thus raising her center of mass 0.6m (returning to its original level). find the height of her center of mass h at the top of the arc.