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A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a non-SI unit of energy equal to 3.6 megajoules (MJ) in SI units, which is the energy delivered by one kilowatt of power for one hour. Kilowatt-hours are a common billing unit for electrical energy supplied by electric utilities.
Energy; system unit code (alternative) symbol or abbrev. notes sample default conversion combinations SI: yottajoule: YJ YJ 1.0 YJ (2.8 × 10 17 kWh) zettajoule: ZJ ZJ 1.0 ZJ (2.8 × 10 14 kWh)
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 ...
Per-unit quantities are the same on either side of a transformer, independent of voltage level; By normalizing quantities to a common base, both hand and automatic calculations are simplified. It improves numerical stability of automatic calculation methods. Per unit data representation yields important information about relative magnitudes.
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]
In the most common calculation, that is, the BTU value of pure gasoline vs gasoline with 10% ethanol, the latter has just over 96% BTU value of pure gasoline. Gasoline BTU varies relating to the Reid vapor pressure (causing easier vaporization in winter blends containing ethanol (ethanol is difficult to start a vehicle on when it is cold out ...
Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power source.
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.