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Thermodynamic work is one of the principal kinds of process by which a thermodynamic system can interact with and transfer energy to its surroundings. This results in externally measurable macroscopic forces on the system's surroundings, which can cause mechanical work, to lift a weight, for example, [1] or cause changes in electromagnetic, [2] [3] [4] or gravitational [5] variables.
The work per unit of charge is defined as the movement of negligible test charge between two points, and is expressed as the difference in electric potential at those points. The work can be done, for example, by generators, (electrochemical cells) or thermocouples generating an electromotive force.
In terms of SI base units, one joule corresponds to one kilogram-square metre per square second (1 J = 1 kg⋅m 2 ⋅s −2). One joule is equal to the amount of work done when a force of one newton displaces a body through a distance of one metre in the direction of that force.
The work done is given by the dot product of the two vectors, where the result is a scalar. When the force F is constant and the angle θ between the force and the displacement s is also constant, then the work done is given by: = If the force is variable, then work is given by the line integral:
Other work terms are added on per system requirements. [11] Each quantity in the equations above can be divided by the amount of substance, measured in moles, to form molar Gibbs free energy. The Gibbs free energy is one of the most important thermodynamic functions for the characterization of a system.
Its published results did much to bring about general acceptance of Joule's work and the kinetic theory. However, in 1848, von Mayer had first had sight of Joule's papers and wrote to the French Académie des Sciences to assert priority. His letter was published in the Comptes Rendus and Joule was quick to react. Thomson's close relationship ...
Quantity (common name/s) (Common) symbol/s Defining equation SI unit Dimension Temperature gradient: No standard symbol K⋅m −1: ΘL −1: Thermal conduction rate, thermal current, thermal/heat flux, thermal power transfer
This article uses the physics sign convention for work, where positive work is work done by the system. Using this convention, by the first law of thermodynamics, The yellow area represents the work done = + where W is work, U is internal energy, and Q is heat. [1] Pressure-volume work by the closed system is defined as: