Which force cannot be expressed in terms of a potential-energy function?

Question

G1 Physics · Accepted Answer

A potential-energy function can be defined for conservative forces. Coulomb force, gravitational force and an ideal spring restoring force are conservative. Friction is non-conservative because its work depends on path and dissipates mechanical energy. Therefore frictional force cannot be represented by a single-valued potential-energy function. Correct option: C.