What is power in physics?

• A. The amount of work done.
• B. Rate at which work is done.
• C. The speed of an object.
• D. The resistance to motion.

Answer: (B)

Power is the rate at which work is done or energy is transferred. Work is the energy you transfer when a force moves something, so power tells you how quickly that transfer happens. Mathematically, power equals work divided by time (P = W/t), and the unit is the watt, which is one joule per second.

For a concrete feel, lifting a box in less time means higher power than lifting it over a longer period, even if the total work (the energy you expend) is similar. Instantaneous power can also be written as P = F · v, force times the velocity in the direction of the force.

The other ideas don’t define power: the amount of work describes energy transferred, not how fast it happens; speed is about how fast an object moves, not how quickly energy is transferred; and resistance to motion refers to forces like friction, not the rate of energy transfer.