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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 ...
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. When the battery delivers its energy, it does so at a certain power, that is, the rate of delivery of the energy.
A human in a sprint has approximately 3 kJ of kinetic energy, [20] while a cheetah in a 122 km/h (76 mph) sprint has approximately 20 kJ. [21] One watt-hour, of electricity or any other form of energy, is 3.6 kJ. megajoule The megajoule is approximately the kinetic energy of a one megagram (tonne) vehicle moving at 161 km/h (100 mph).
Thomas Young, the first person to use the term "energy" in the modern sense. The word energy derives from the Ancient Greek: ἐνέργεια, romanized: energeia, lit. 'activity, operation', [4] which possibly appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a ...
Electrical energy is energy related to forces on electrically charged particles and the movement of those particles (often electrons in wires, but not always). This energy is supplied by the combination of current and electric potential (often referred to as voltage because electric potential is measured in volts) that is delivered by a circuit (e.g., provided by an electric power utility).
Energy conversion efficiency depends on the usefulness of the output. All or part of the heat produced from burning a fuel may become rejected waste heat if, for example, work is the desired output from a thermodynamic cycle. Energy converter is an example of an energy transformation.
In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic [1] and gravitational radiation. As energy, its SI unit is the joule (J). The quantity of radiant energy may be calculated by integrating radiant flux (or power ) with respect to time .
Storage capacity is the amount of energy extracted from an energy storage device or system; usually measured in joules or kilowatt-hours and their multiples, it may be given in number of hours of electricity production at power plant nameplate capacity; when storage is of primary type (i.e., thermal or pumped-water), output is sourced only with ...