The total mechanical energy of a system
A) is either all kinetic energy or all potential energy, at any one instant.
B) can never be negative.
C) is equally divided between kinetic energy and potential energy.
D) is constant only if nonconservative forces act.
E) is constant only if conservative forces act.

Question

Quizplus · Accepted Answer

The total mechanical energy of a system is constant only if conservative forces (like gravity or spring forces) act on the system. Nonconservative forces (like friction) cause the mechanical energy to change.

The Total Mechanical Energy of a System