The rate at which work is performed is defined as what?

• A. Energy
• B. Velocity
• C. Power
• D. Work

Answer: (C)

Power is the rate at which work is done, meaning how quickly energy is transferred over time. When the same amount of work happens in less time, power is higher; taking longer lowers power. This is captured by P = dW/dt, with common units of joules per second (watts). This differs from energy (the total capacity to do work) and from velocity (motion speed in a direction, not the rate of energy transfer). For example, lifting a certain amount of work in 4 seconds gives 50 W, while doing the same amount in 1 second gives 200 W.