Under what condition does potential energy exist?

Potential energy exists in situations where an object possesses the ability to do work due to its position or configuration within a force field. This is why the presence of a force field—such as gravitational, electric, or magnetic—is crucial. When an object is placed within such a field, it can store energy based on its position relative to other objects or fields, thus having potential energy.

For example, a rock held at a height has gravitational potential energy due to the Earth's gravitational field acting on it. If it falls, that potential energy can be converted into kinetic energy. This relationship highlights that potential energy is not solely dependent on the object being stationary; rather, it is the object's position in relation to forces acting on it that defines its potential energy. Therefore, under the condition where an object with mass is within a force field, the potential energy is present, validating the correctness of this choice.