Classical thermodynamics, heat transfer Definition

Thermodynamic work

Builds on Thermodynamic system Quasistatic process

Definition

Let $\Sigma$ be a thermodynamic system. The work $W$ done on $\Sigma$ in a process is the energy transferred to $\Sigma$ by macroscopic forces of the surroundings. These forces act through changes of external parameters of $\Sigma$ , such as its volume. Transfers of energy as heat or with matter are not work. For a quasistatic process $\gamma$ of a fluid with pressure $p$ and volume $V$ , $W = -\int_\gamma p \, dV.$

Remarks

Compress $n$ moles of ideal gas quasistatically at constant temperature $T$ from volume $V_1$ to $V_2 < V_1$ . Then $p = nRT/V$ , and $W = -\int_{V_1}^{V_2} nRT \, dV / V = nRT \ln(V_1 / V_2) > 0$ . Heating a gas in a rigid container is not work: the volume does not change, and the energy enters as heat. Some texts write $W$ for the work done by the system, which changes the sign.

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Tag	`WN4H8255HN`
URI	`m2://WN4H8255HN`
Kind	definition
Writing	W0 stub
MSC	80A05, 80A10
Defines	Thermodynamic work
Uses	Thermodynamic system, Quasistatic process
Changed	3 November 2026

Thermodynamic work

Definition

Remarks

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