Worked Example: Power

A mechanical hoist performs 180,000 Joules (180 kJ) of work to lift a heavy load. If the hoist completes this task in exactly 5.0 seconds, calculate the average mechanical power delivered by the hoist.

Power ($P$) is defined as the work done ($W$) divided by the time ($t$) it takes to do the work: $P = \frac{W}{t}$

The calculated power of 36 kW indicates the required mechanical output rate. This value bridges mechanical engineering with electrical engineering: to select a suitable electric motor for this hoist, an engineer would start with this 36 kW mechanical requirement, then apply efficiency factors to determine the required electrical input power.