What formula is used to find the amount of work done when an object is moved across the floor?

• A. Work = Force × Distance.
• B. Power = Force × Distance.
• C. Work = Distance × Time.
• D. Energy = Mass × Acceleration.

Answer: (A)

Work is the energy transferred when a force moves an object along a distance in the direction of that force. The amount of work done is the product of the force applied and the distance the object travels: Work = Force × Distance. If the force isn’t exactly along the direction of motion, you use the component of the force in the direction of movement, giving Work = (Force cos theta) × Distance. This is the situation when moving an object across the floor: you’re applying a force that causes displacement, so the work equals your push times how far it goes.

Power is about how quickly that work is done, not the total amount, so Power = Force × Distance isn’t correct. The expression Work = Distance × Time would not produce energy in the proper units, and Energy = Mass × Acceleration doesn’t describe work (kinetic energy is (1/2) m v^2).