Question

The total energy of an isolated system is conserved under which of the following conditions?

• A. Only when the forces involved are conservative
• B. Only when friction can be neglected
• C. Only when nonconservative forces are involved
• D. Always
• E. Technically never

Answer 1

Answer: (D)

Always

The law of conservation of energy states that total energy of an isolated system is always conserved , whereas when work is done by or against a non-conservative force total mechanical energy is not conserved , but total energy is conserved always .