A bungee jumper leaps from a platform and is slowed down by an elastic bungee cord, as illustrated. As the jumper begins the jump, his initial gravitational potential energy is changed into kinetic energy and elastic potential energy in the cord. In which stage of the jump are all three forms of energy greater than zero?
- Aon the platform before the jump
- Bon the way down before the cord has started to extend
- Con the way down as he decelerates
- Dat the bottom of the jump when he is stationary