ASPECt
Energy: Forms, Transformation, Transfer, and Conservation
Item RG113002: As two oppositely charged object move closer to each other, the electrostatic potential energy of the system decreases, and the kinetic energy of the moving object increases.
A device shoots a negatively charged particle in a straight line, as pictured in Figure 1 below.
A positively charged object is placed near the path of the negatively charged particle. The attraction between the particle and the object causes the particle to change course from its original path, as pictured in Figure 2.
How does the energy of the particle-object system change as the particle travels from Position 1 to Position 2 as shown in Figure 2 before the particle hits the object? (Assume the effect of gravity is negligible and can be ignored.)
- The electrostatic potential energy of the system decreases, and the kinetic energy of the particle increases.
- The electrostatic potential energy of the system decreases, and the kinetic energy of the particle decreases.
- The electrostatic potential energy of the system increases, and the kinetic energy of the particle decreases.
- The electrostatic potential energy of the system increases, and the kinetic energy of the particle increases.
- Distribution of Responses
- Scale Score for Item Difficulty
(200[Easy]-800[Difficult]) - 536
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 288 | 1121 | 26% |
| Grades | |||
| 4–5 | N/A | N/A | N/A |
| 6–8 | 160 | 665 | 24% |
| 9–12 | 128 | 456 | 28% |
| Gender | |||
| Male | 146 | 551 | 26% |
| Female | 137 | 551 | 25% |
| Primary Language | |||
| English | 245 | 982 | 25% |
| Other | 32 | 113 | 28% |
- Disciplinary Core Ideas
- PS3.A Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed.
PS3.C When two objects interacting through a field change relative position, the energy stored in the field is changed. - NRC Framework
- Energy is also stored in the electric fields between charged particles and the magnetic fields between magnets, and it changes when these objects are moved relative to one another.