Mechanical power for motors is usually expressed as what unit?

The correct answer is horse power because this unit has traditionally been used to measure the power output of engines and motors in a more relatable manner, especially in the context of automotive and industrial applications. One horsepower is equivalent to 746 watts, making it a practical unit for expressing the performance of larger machinery and engines where users might prefer a more intuitive scale than watts.

While watts and kilowatts are also valid measurements for electrical and mechanical power, they tend to be used in more formal calculations or specifications rather than in everyday language or common industrial contexts. Joules are a unit of energy, not power, so they are not used to express mechanical power directly. Therefore, horsepower remains the standard unit often encountered in discussions related to motors and engines, reinforcing its relevance in this context.