Which of the following describe the law of conservation of energy? Which of the following describe the law of conservation of energy? A. A roller coaster's potential energy at the top of a hill is changed into kinetic energy as the roller coaster moves down the hill. B. All of the above. C. A pendulum bob looses potential energy as it swings from a higher to lower elevation, but gains kinetic energy. D. A car at the top of a ramp having potential energy that is converted into kinetic energy as the car rolls down the ramp.