Editing Thermodynamic system (section)

{{short description|Body of matter in a state of internal equilibrium}}
{{Use dmy dates|date=January 2020}}
[[File:Diagram Systems.svg|thumb|Properties of isolated, closed, and open thermodynamic systems in exchanging energy and matter]]

A '''thermodynamic system''' is a body of [[matter]] and/or [[radiation]] separate from its surroundings that can be studied using the laws of [[thermodynamics]].

Thermodynamic systems can be passive and active according to internal processes. According to internal processes, passive systems and active systems are distinguished: passive, in which there is a redistribution of available energy, active, in which one type of energy is converted into another.

Depending on its interaction with the environment, a thermodynamic system may be an [[isolated system]], a [[Closed system#In thermodynamics|closed system]], or an [[Open system (systems theory)|open system]]. An isolated system does not exchange matter or energy with its surroundings. A closed system may exchange heat, experience forces, and exert forces, but does not exchange matter. An open system can interact with its surroundings by exchanging both matter and energy.

The physical condition of a thermodynamic system at a given time is described by its ''state'', which can be specified by the values of a set of thermodynamic state variables. A thermodynamic system is in [[thermodynamic equilibrium]] when there are no [[Macroscopic scale|macroscopically]] apparent flows of matter or energy within it or between it and other systems.{{sfn|Rex|Finn|2017|p=1&ndash;4}}

[[File:system boundary2.svg|200px|thumb]]