Irving, a cat, has a favorite toy that is made up of a squeaky ball at the end of a string. The toy makes up a closed system. Irving’s owner dangles the toy so that the ball swings down and then swings back up again. Ignoring any friction, how are kinetic and potential energy related to each other as the ball swings back and forth?, a cat, has a favorite toy that is made up of a squeaky ball at the end of a string. The toy makes up a closed system. Irving’s owner dangles the toy so that the ball swings down and then swings back up again. Ignoring any friction, how are kinetic and potential energy related to each other as the ball swings back and forth?