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The joule (/ dʒ uː l / JOOL, or / dʒ aʊ l / JOWL; symbol: J) is the unit of energy in the International System of Units (SI). [1] It is equal to the amount of work done when a force of one newton displaces a mass through a distance of one metre in the direction of that force.
The SI unit for specific energy is the joule per kilogram (J/kg). Other units still in use worldwide in some contexts are the kilocalorie per gram (Cal/g or kcal/g), mostly in food-related topics, and watt-hours per kilogram (W⋅h/kg) in the field of batteries.
Energy is defined via work, so the SI unit of energy is the same as the unit of work – the joule (J), named in honour of James Prescott Joule [1] and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton metre and, in terms of SI base units
In the SI system (expressing the ratio E / m in joules per kilogram using the value of c in metres per second): [35] E / m = c 2 = (299 792 458 m/s) 2 = 89 875 517 873 681 764 J/kg (≈ 9.0 × 10 16 joules per kilogram). So the energy equivalent of one kilogram of mass is 89.9 petajoules; 25.0 billion kilowatt-hours (≈ 25,000 ...
1 kg ⋅m 2 ⋅s −2 ... One joule is approximately equal to 0.7376 ft-lbs. [16] ... These formulas show that work is the energy associated with the action of a ...
An electronvolt is the amount of energy gained or lost by a single electron when it moves through an electric potential difference of one volt.Hence, it has a value of one volt, which is 1 J/C, multiplied by the elementary charge e = 1.602 176 634 × 10 −19 C. [2]
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 SI unit of specific heat capacity is joule per kelvin per kilogram, J⋅kg −1 ⋅K −1. [2] For example, the heat required to raise the temperature of 1 kg of water by 1 K is 4184 joules, so the specific heat capacity of water is 4184 J⋅kg −1 ⋅K −1. [3]