What are the common units for measuring power?

The common units for measuring power are the watt (W), kilowatt (KW), megawatt (MW), and horsepower (hp).

Power, in the context of physics, is the rate at which work is done or energy is transferred. The standard unit of power in the International System of Units (SI) is the watt, symbolised by 'W'. This unit is named after James Watt, a Scottish inventor and mechanical engineer. One watt is defined as one joule per second, indicating the rate of energy conversion or transfer.

Another commonly used unit is the kilowatt (KW), which is equal to 1,000 watts. This unit is often used in practical situations like measuring the power of engines or electric devices. For instance, the power of an electric kettle might be rated in kilowatts.

The megawatt (MW) is a larger unit of power, equivalent to one million watts or 1,000 kilowatts. This unit is typically used in the context of large power plants or power grids. For example, a nuclear power plant might have a capacity of several hundred megawatts.

Lastly, the horsepower (hp) is a unit of power commonly used to measure the power output of engines, particularly in cars and other vehicles. It was originally defined by James Watt to compare the output of steam engines with the power of draft horses. One horsepower is approximately equivalent to 746 watts.

In summary, the watt, kilowatt, megawatt, and horsepower are all common units for measuring power. Each is used in different contexts, depending on the scale of power being measured.