What term describes the rate at which work is done?

• A. Power
• B. Gravitational Potential Energy
• C. Inertia
• D. Buoyant Force

Answer: (A)

Power is the rate at which work is done. It tells you how quickly energy is transferred by a force acting over a distance. If you do the same amount of work in less time, you’re doing the work faster, so the power is higher. Mathematically, instantaneous power is the rate of change of work: P = dW/dt, and for a constant force, P = F · v (the force times velocity, taking only the component in the direction of motion). The average power over a time interval is W/Δt. The unit is the watt, equal to one joule per second. For example, lifting a crate quickly transfers energy in less time, yielding greater power than lifting it slowly, even if the total work is similar.

Others describe energy or forces but not the rate of transfer: gravitational potential energy is energy due to height, inertia is resistance to changes in motion, and buoyant force is the upward force from a fluid.