A 0.50-kg ball on the end of a rope is moving in a vertical circle of radius 3.0 m near the surface of the Earth where the acceleration due to gravity, g, is 9.8 m/s2.
Point A is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C.
The ball moves on the circle from A to C under the influence of gravity alone. If the kinetic energy of the ball is 35 J at A, what is its kinetic energy at C?