Original Project
Energy: Forms, Transformation, Transfer, and Conservation
Item NG015003: 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 do the gravitational potential energy and the motion energy (kinetic energy) of the ball change as the ball rolls down the ramp? Why?
- The gravitational potential energy decreases and the motion energy increases. The gravitational potential energy is transformed into motion energy as the ball rolls down the ramp.
- The gravitational potential energy decreases and the motion energy increases. As soon as the ball starts moving it no longer has gravitational potential energy; it has only motion energy.
- The motion energy and gravitational potential energy both decrease. Both forms of energy are used up as the ball moves and are not transformed into any other form of energy.
- The gravitational potential energy and the motion energy both stay the same. One form of energy cannot be transformed into a different form of energy.
- Distribution of Responses
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 1401 | 3013 | 47% |
| Grades | |||
| 6–8 | 803 | 1890 | 42% |
| 9–12 | 597 | 1114 | 54% |
| Gender | |||
| Male | 711 | 1459 | 49% |
| Female | 673 | 1506 | 45% |
| Primary Language | |||
| English | 1291 | 2730 | 47% |
| Other | 81 | 198 | 41% |
- NRC Framework
- PS3.A …lifting an object increases the stored energy in the gravitational field between that object and Earth (gravitational potential energy) compared to that for the object at Earth’s surface; when the object falls, the stored energy decreases and the object’s kinetic energy increases. (5, 121)
- PS3.A Any change in potential energy is accompanied by changes in other forms of energy within the system, or by energy transfers into or out of the system.