At the top of a swing move or cause to move back and forth or from side to side while suspended or on an axis , the mass has the maximum store of gravitational potential energy. As the pendulum a weight hung from a fixed point so that it can swing freely. Used in clocks to help the mechanism keep time swings move or cause to move back and forth or from side to side while suspended or on an axis downwards, this is gravitational potential energy is transferred into kinetic energy. The mass has the maximum amount of kinetic energy at the bottom of the swing move or cause to move back and forth or from side to side while suspended or on an axis where it is moving with the greatest speed.