What is the amount of work that can be performed by a force, subject to a conservation law?

• A. Power
• B. Momentum
• C. Energy
• D. Charge

Answer: (C)

Work is the transfer of energy: when a force acts over a distance, it moves energy from one form to another. In a system where energy is conserved, the total amount of energy available sets the limit on how much work can be done. That’s why energy is the quantity that describes the amount of work a force can perform. Power, on the other hand, is just the rate at which work is done, not the total amount. Momentum describes motion and impulse, not the total work under a conservation law, and charge is unrelated to this mechanical context.