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A kilowatt-hour is a unit of energy. Kilowatt per hour would be a rate of change of power flow with time. Work is the amount of energy transferred to a system; power is the rate of delivery of energy. Energy is measured in joules, or watt-seconds. Power is measured in watts, or joules per second. For example, a battery stores energy.
battery, Nickel–metal hydride (NiMH), low power design as used in consumer batteries [29] 0.4: 1.55: Liquid Nitrogen: 0.349: Water – Enthalpy of Fusion: 0.334: 0.334: battery, Zinc–Bromine flow (ZnBr) [30] 0.27: battery, Nickel–metal hydride (NiMH), High-Power design as used in cars [31] 0.250: 0.493: battery, Nickel–Cadmium (NiCd ...
In battery or electric vehicles, calculating the vehicle's overall efficiency of useful work begins with the charge–discharge rate of the battery pack, generally 80% to 90%. Next is the conversion of stored energy to distance traveled under power.
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 ...
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)
The watt, kilogram, joule, and the second are part of the International System of Units (SI). The hour is not, though it is accepted for use with the SI.Since a watt equals one joule per second and because one hour equals 3600 seconds, one watt-hour per kilogram can be expressed in SI units as 3600 joules per kilogram.
In the International System of Units, the unit of power is the watt, equal to one joule per second. Power is a scalar quantity. Specifying power in particular systems may require attention to other quantities; for example, the power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, and ...
The work required to produce one watt of power for one second, or one watt-second (W⋅s) (compare kilowatt-hour, which is 3.6 megajoules). This relationship can be used to define the watt. The joule is named after James Prescott Joule.