Final answer:
When a potential explicitly depends on time, energy is not conserved. However, if we take into account what is causing this potential, the total energy of the combined system can be conserved.
Step-by-step explanation:
When a potential explicitly depends on time, energy is not conserved. However, if we take into account what is causing this potential (for example, a machine moving some object(s)), the total energy of the combined system can be conserved. This is because when we consider the combined system, we include the energy associated with the external force or agent causing the potential. In general, the conservation of energy depends on the specific details of the system and the forces acting on it.