Key Idea: Gravitational potential energy is associated with the separation of mutually attracting masses.
Students should know that:
- Because all objects exert an attractive gravitational force on all other objects, whenever two objects are separated by some distance, the objects tend to move toward each other when they are released. (If they do not move toward each other, it is because some other force greater than the force of gravity acts to oppose their coming together.) The energy the objects have due to their separation is called gravitational potential energy.
- The gravitational potential energy of a system of two objects depends on the mass of the two objects and the distance between their centers of mass.
- Increasing the distance between the objects, increases the amount of gravitational potential energy in the system that is made up of those two objects. Decreasing the distance between the objects, decreases the amount of gravitational potential energy.
- The gravitational potential energy of a system depends on the distance between the objects and not on how the objects in the system came to be in that configuration.
Boundaries:
- Assessment items use the phrase “gravitational potential energy” and not “gravitational energy” because students often confuse “gravitational energy” with “gravitational force.”
- Assessment items expect students to compare relative distances and masses to determine relative amounts of gravitational potential energy. Students are not expected to calculate the exact amount of gravitational potential energy.
| Item ID Number |
Knowledge Being Assessed | Grades 4–5 |
Grades 6–8 |
Grades 9–12 |
Select This Item for My Item Bank |
|---|---|---|---|---|---|
N/A | 49% |
51% |
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N/A | 39% |
48% |
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N/A | 32% |
34% |
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N/A | 29% |
29% |
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N/A | 22% |
23% |
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N/A | 19% |
21% |
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Misconception |
Student Misconception |
Grades 4–5 |
Grades |
Grades |
|---|---|---|---|---|
N/A | 34% |
36% | ||
N/A | 26% |
34% | ||
N/A | 22% |
22% | ||
Gravitational potential energy results only from interactions with the Earth (suspected). | N/A | 21% |
20% | |
N/A | 20% |
15% | ||
N/A | 20% |
13% |
Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.