Question

If a system left over a period of time, What happens to the amount of its usable energy?

• A. increases
• B. decreases
• C. remains constant
• D. increases until the heat of friction equal the original potential energy in the system
• E. decreases until no heat is left in the system

Answer 1

Answer: (C)

remains constant

If the system is closed, there would be no interaction with the surroundings. Then according to the law of conservation of energy, the energy of the closed system would remain unchanged or constant.