A boy swings a rubber ball attached to a string over his head in a horizontal, circular path. The piece of string is 0.735 m long and the ball makes 159 complete turns each minute. What is the ball's centripetal acceleration?

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?