First Law Of Thermodynamics

Domain	Definitions
Aerospace	A statement of the conservation of energy for thermodynamic systems (not necessarily in equilibrium). The fundamental form requires that the heat absorbed by the system serve either to raise the internal energy of the system or to do work on the environment: dq = du + dw where dq is the heat added per unit mass; du is the increment of specific internal energy; and dw is the specific work done by the system on the environment. Although dq and dw are not perfect differentials, their difference, du, is always a perfect differential. Example of the application of this equation: in an adiabatic free expansion of gas into a vacuum, all three terms are zero. For reversible processes the mechanical work is equal to the expansion against the pressure forces, i.e., dw = pdv where p is the pressure and v is the specific volume. For a perfect gas, the internal energy change is proportional to the temperature change, du = cvdT where cv is the specific heat at constant volume and T is the Kelvin temperature. Therefore, the form of the first law usually used in meteorological applications is dq = cvdT + pdv Use of the equation of state yields an alternative form, dq = cpdT - dp where cp is the specific heat at constant pressure. For open systems the variation of total rather than specific quantities is important: dQ = dU + pdV - hdm where Q is the total heat; U is the total internal energy; V is the volume; m is the mass of the system; and h is the specific enthalpy. If a system contains the possibility of nonmechanical work, such as work done against an electric field, this work must be included in the first law.See second law of thermodynamics, third law of thermodynamics, energy equations. (references)
Electrical Engineering	The total energy of an isolated system remains constant irrespective of whatever internal changes may take place. Energy disappearing in one form reappears in another. Source: European Union. (references)
Energy	States that energy cannot be created or destroyed, but only changed from one form to another. First Law efficiency measures the fraction of energy supplied to a device or process that it delivers in its output. Also called the law of conservation of energy. (references)
Source: compiled by the editor from various references; see credits.

Frequency of Internet Keywords: First Law Of Thermodynamics

Modern Translations: First Law Of Thermodynamics

Language		Translations for "first law of thermodynamics"; alternative meanings/domain in parentheses.
Danish		loven om energibevarelse (energy conservation law), energibevarelsesloven (energy conservation law). (various references)

Dutch		wet van het behoud van energie (energy conservation law). (various references)

Finnish		energian säilyvyyden laki (energy conservation law). (various references)

French		loi de conservation de l'énergie. (various references)

German		Satz der Energieerhaltung (energy conservation law). (various references)

Greek		νόμος διατήρησης της ενέργειας (energy conservation law). (various references)

Italian		legge della conservazione dell'energia (energy conservation law). (various references)

Pig Latin		irstfay awlay ofay ermodynamicsthay

Portuguese		lei da conservação de energia (energy conservation law). (various references)

Spanish		ley de conservación de la energía (energy conservation law). (various references)

Swedish		lagen om energins oförstörbarhet (energy conservation law). (various references)
Source: compiled by the editor from various translation references.