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The dimension of power is energy divided by time. 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.
Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time. For example, when a light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360 kJ. This same amount of energy would light a 40 ...
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] This is a measurement of average power consumption, meaning the average rate at which energy is transferred ...
The notation kW/h for the kilowatt-hour is incorrect, as it denotes kilowatt per hour. The hour is a unit of time listed among the non-SI units accepted by the International Bureau of Weights and Measures for use with the SI. [6] An electric heater consuming 1,000 watts (1 kilowatt) operating for one hour uses one kilowatt-hour of energy.
Electric power is the rate of transfer of electrical energy within a circuit.Its SI unit is the watt, the general unit of power, defined as one joule per second.Standard prefixes apply to watts as with other SI units: thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively.
Watt determined that a horse could turn a mill wheel 144 times in an hour (or 2.4 times a minute). [6] The wheel was 12 feet (3.7 m) in radius; therefore, the horse travelled 2.4 × 2π × 12 feet in one minute. Watt judged that the horse could pull with a force of 180 pounds-force (800 N). [7] So:
= 1 kWh (kilowatt-hour) (used for electricity) [59] 4.2×10 6 J: Energy released by explosion of 1 kilogram of TNT [59] [99] 6.1×10 6 J Kinetic energy of the 4 kg tungsten APFSDS penetrator after being fired from a 120mm KE-W A1 cartridge with a nominal muzzle velocity of 1740 m/s. [113] [114] 8.4×10 6 J
1.1 × 10 3 W tech: power of a microwave oven: 1.366 × 10 3 W astro: power per square meter received from the Sun at the Earth's orbit: 1.5 × 10 3 W tech: legal limit of power output of an amateur radio station in the United States up to 2 × 10 3 W biomed: approximate short-time power output of sprinting professional cyclists and ...