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This is the definition declared in the modern International System of Units in 1960. [13] The definition of the joule as J = kg⋅m 2 ⋅s −2 has remained unchanged since 1946, but the joule as a derived unit has inherited changes in the definitions of the second (in 1960 and 1967), the metre (in 1983) and the kilogram . [14]
2×10 −23 J: Average kinetic energy of translational motion of a molecule in the Boomerang Nebula, the coldest place known outside of a laboratory, at a temperature of 1 kelvin [6] [7] 10 −22 2–3000×10 −22 J Energy of infrared light photons [8] 10 −21: zepto-(zJ) 1.7×10 −21 J 1 kJ/mol, converted to energy per molecule [9] 2.1×10 ...
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
By definition, the change in electrostatic potential energy, U E, of a point charge q that has moved from the reference position r ref to position r in the presence of an electric field E is the negative of the work done by the electrostatic force to bring it from the reference position r ref to that position r.
His letter was published in the Comptes Rendus and Joule was quick to react. Thomson's close relationship with Joule allowed him to become dragged into the controversy. The pair planned that Joule would admit von Mayer's priority for the idea of the mechanical equivalent but to claim that experimental verification rested with Joule.
joule (J) Lagrangian density: joule per cubic meter (J/m 3) length: meter (m) ℓ: azimuthal quantum number: unitless magnetization: ampere per meter (A/m) moment of force often simply called moment or torque newton meter (N⋅m) mass: kilogram (kg)
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.
In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.