Item RG127002: In a windmill, 100% of the kinetic energy from the wind cannot be converted into electrical energy because a small amount of energy will always be converted into thermal energy and transferred to the environment, during each transfer and transformation of energy.
A windmill is a device that uses energy from wind to turn a generator. The generator then uses that energy to generate electricity.
Modern windmills cannot convert all of the kinetic energy absorbed from the wind into electrical energy. Engineers say that it is unlikely to ever get 100% conversion. Why can’t 100% of the kinetic energy from the wind be converted into electrical energy?
- During each transfer and transformation of energy, a small amount of energy will always be destroyed.
- During each transfer and transformation of energy, a small amount of energy will always be converted into thermal energy and transferred to the environment.
- During each transfer and transformation of energy, a small amount of energy will be destroyed and a small amount will be transferred to the environment.
- The windmill is in an open system, and 100% conversion is only possible in closed systems where energy cannot enter or leave.
- Distribution of Responses
- Scale Score for Item Difficulty
(200[Easy]-800[Difficult]) - 493
- Students Responding Correctly
Group | Correct | Total | Percent |
---|---|---|---|
Overall | 2679 | 5875 | 46% |
Grades | |||
4–5 | 170 | 437 | 39% |
6–8 | 1274 | 3071 | 41% |
9–12 | 1235 | 2367 | 52% |
Gender | |||
Male | 1272 | 2833 | 45% |
Female | 1339 | 2913 | 46% |
Primary Language | |||
English | 2377 | 5199 | 46% |
Other | 222 | 513 | 43% |
- Disciplinary Core Ideas
- PS3.B Uncontrolled systems always evolve toward more stable states--that is, toward more uniform energy distribution (e.g., water flows downhill, objects hotter than their surrounding environment cool down).
- NRC Framework
- PS3.D When machines or animals “use” energy (e.g., to move around), most often the energy is transferred to heat the surrounding environment.