Which of the following statements is/are true? check all that apply. check all that apply. the total mechanical energy of a system is constant only if all the forces doing work on it are nonconservative. the total mechanical energy of a system is constant only if all the forces doing work on it are conservative. the total mechanical energy of a system is equally divided between kinetic and potential energy. mechanical energy can be dissipated to nonmechanical forms of energy. the total mechanical energy of a system, at any one instant, is either all kinetic or all potential energy.