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In the International System of Units (SI), the unit of power is the watt (W), which is equal to one joule per second. Other common and traditional measures are horsepower (hp), comparing to the power of a horse; one mechanical horsepower equals about 745.7 watts.
The kilowatt is typically used to express the output power of engines and the power of electric motors, tools, machines, and heaters. It is also a common unit used to express the electromagnetic power output of broadcast radio and television transmitters. One kilowatt is approximately equal to 1.34 horsepower.
The watt, symbol W, is the SI coherent derived unit of power, or rate of energy transfer. It is the special name for the kilogram metre squared per second cubed, symbol kg m 2 s -3 . One watt is equal to the transfer of one joule in one second .
A unit of electrical energy, particularly for utility bills, is the kilowatt-hour (kWh); [3] one kilowatt-hour is equivalent to 3.6 megajoules. Electricity usage is often given in units of kilowatt-hours per year or other periods. [4]
2 lip 2024 · The Joule (symbol: J) is the official unit of energy in the International System of Units (SI). It is named after the English physicist James Prescott Joule. One joule represents the amount of energy transferred when applying a force of one newton over a distance of one meter.
3 lip 2024 · The Watt is the SI unit of power named after James Watt. It measures the rate at which work is done or energy is transferred when one joule is expended in one second. It is universally used in science, engineering, and everyday electrical appliances to quantify power.
The standard metric unit of power is the Watt. As is implied by the equation for power, a unit of power is equivalent to a unit of work divided by a unit of time. Thus, a Watt is equivalent to a Joule/second. For historical reasons, the horsepower is occasionally used to describe the power delivered by a machine.
