Potential energy arises when_____________.
a. we consider only conservative forces
b. the system is isolated
c. thermal energy can be neglected
d. the work from external forces is zero
e. interaction are included within the system
The Correct Answer and Explanation is:
Correct Answer: e. interactions are included within the system
Explanation:
Potential energy is a form of mechanical energy that is associated with the position or configuration of objects within a system. It arises only when interactions between parts of the system are considered. Therefore, option (e) — interactions are included within the system — is the correct choice.
To understand this better, consider that potential energy is not an inherent property of a single object but rather a property of a system of objects that interact via conservative forces such as gravity, spring (elastic) force, or electrostatic force. These interactions store energy in a potential form. For example:
- A mass held above the ground has gravitational potential energy due to its interaction with Earth’s gravitational field.
- A compressed spring has elastic potential energy due to the interaction between the spring’s particles resisting deformation.
When interactions are excluded, the potential energy concept breaks down because the system no longer stores energy due to configuration or position. Without considering interactions, we can only account for kinetic energy or thermal energy, not potential energy.
Let’s evaluate the other options:
- (a) “we consider only conservative forces” – Conservative forces like gravity are indeed associated with potential energy, but just considering them isn’t enough; interactions must still be included.
- (b) “the system is isolated” – Isolation prevents energy exchange with the surroundings but doesn’t determine the presence of potential energy.
- (c) “thermal energy can be neglected” – Neglecting thermal energy helps simplify analysis but does not cause potential energy to arise.
- (d) “the work from external forces is zero” – This condition relates to conservation of energy, not the presence of potential energy.
In conclusion, potential energy exists when the internal interactions among the system’s components are taken into account, making option (e) the most accurate.