The rate at which work is performed is called?

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

Answer: (A)

Power is the rate at which work is done or energy is transferred. The word rate means per unit time, so power equals the amount of work divided by the time it takes (P = W / t). The units are watts, which are joules per second. This also aligns with the idea that instantaneous power can be found as the force applied times how fast the point of application moves, written as P = F · v. That means doing the same amount of work in less time increases power, while performing work slowly lowers it. Distinguish this from work, which is the total energy transferred; energy, on the other hand, is the capacity to do work. Velocity is simply speed, not the rate of energy transfer.