What are the two equations for calculating power?

What are the two equations for calculating power?

• A. Power(W) = energy transferred(J) / time(s) and Power(W) = work done(J) / time(s)
• B. Power(W) = energy transferred(J) × time(s)
• C. Power(W) = time(s) / energy transferred(J)
• D. Power(W) = force(N) × velocity(m/s)

Answer: (A)

Power is the rate at which energy is transferred or transformed. The two general ways to calculate it are by dividing the amount of energy transferred by the time taken, and by dividing the work done by the time taken. Both give power in watts because 1 joule per second equals 1 watt. For example, if a device transfers 60 joules of energy in 10 seconds, its power is 60/10 = 6 W. The similar idea that power equals force times velocity (P = F × v) is a useful instantaneous form in mechanics when the force and motion are in the same direction, but the broad definitions above are the standard ways to compute power in general.

Power is the rate at which energy is transferred or transformed. The two general ways to calculate it are by dividing the amount of energy transferred by the time taken, and by dividing the work done by the time taken. Both give power in watts because 1 joule per second equals 1 watt. For example, if a device transfers 60 joules of energy in 10 seconds, its power is 60/10 = 6 W. The similar idea that power equals force times velocity (P = F × v) is a useful instantaneous form in mechanics when the force and motion are in the same direction, but the broad definitions above are the standard ways to compute power in general.