ASPECt
Energy: Forms, Transformation, Transfer, and Conservation
Item RG114002: When two balls collide, a small amount of energy was transferred to the environment as thermal energy.
A student rolls a ball down a ramp toward an identical stationary ball.
He determines that the total energy of the two balls just after the collision is slightly lower than the total energy of the two balls before they collided. Why is the total energy of the two balls lower after the balls collide?
- A small amount of energy was destroyed in the collision.
- A small amount of energy was transferred to the environment as thermal energy.
- The student made an error; the total energy of the two balls should be higher after the collision because the first ball actually gained energy as it rolled down the hill.
- The student made an error; the total energy of the two balls should not change because the amount of energy in a system cannot change.
- Distribution of Responses
- Scale Score for Item Difficulty
(200[Easy]-800[Difficult]) - 522
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 1139 | 3705 | 31% |
| Grades | |||
| 4–5 | 198 | 681 | 29% |
| 6–8 | 429 | 1569 | 27% |
| 9–12 | 512 | 1455 | 35% |
| Gender | |||
| Male | 528 | 1674 | 32% |
| Female | 573 | 1926 | 30% |
| Primary Language | |||
| English | 999 | 3306 | 30% |
| Other | 96 | 274 | 35% |
- Disciplinary Core Ideas
- PS3.B Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, thereby changing their motion. In such collisions, some energy is typically also transferred to the surrounding air; as a result, the air gets heated and sound is produced.
PS3.D Although energy cannot be destroyed, it can be converted to less useful forms--for example, to thermal energy in the surrounding environment.