Horsepower is the measurement used for defining the work done in a period of time.

• A. Power is the measurement of work done per unit time.
• B. Torque is the measurement of rotational speed.
• C. Energy is the measurement of force.
• D. Velocity is the measurement of distance over time.

Answer: (A)

The main idea is comparing work and how fast that work is done. Power is the rate at which work is done, meaning work per unit time. Horsepower is a unit used to express that rate. So saying horsepower defines work done over a period is really about describing how quickly work is being done, not just how much work is done in total. In formula terms, power P equals work W divided by time t (P = W/t); it can also be written as P = F·v, linking force and speed.

Torque describes rotational turning force, not a rate of doing work. Energy is the total amount of work that could be done or has been done, not the rate. Velocity is speed—distance over time—not the rate of doing work.