## Item NG015004: As a ball rolls down a ramp, the gravitational potential energy of the ball decreases and the motion energy of the ball increases because gravitational potential energy is transformed into motion energy.

A student holds a ball at the top of a ramp.  He lets go of the ball, and the ball speeds up as it rolls down the ramp.

How and why do the gravitational potential energy and the kinetic energy (motion energy) of the ball change as the ball rolls down the ramp?

1. The gravitational potential energy decreases, and the kinetic energy increases because as the ball rolls down the ramp, the gravitational potential energy is converted into kinetic energy.
2. The gravitational potential energy decreases, and the kinetic energy increases because as soon as the ball starts moving, it no longer has gravitational potential energy, only kinetic energy.
3. The kinetic energy and gravitational potential energy both decrease because as the ball moves, both forms of energy are used up and are not converted into any other form of energy.
4. The gravitational potential energy and the kinetic energy both stay the same because one form of energy cannot be converted into a different form of energy.