isothermal change

physics

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Last updated

June 29, 2026

Quick Summary

An isothermal change in physics refers to a process where a system's temperature remains constant. This occurs when a gas expands and does work, but it must absorb heat from its surroundings to maintain a steady temperature. If the gas were not to absorb heat, it would cool down as it expands, or heat up if compressed.1

This concept is a simplified model used to illustrate thermodynamic principles, particularly concerning heat engines. The ideal gas law, which describes the behavior of gases, relates pressure, volume, and temperature, and is fundamental to understanding isothermal processes.2

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thermodynamics
Isothermal and adiabatic processes
Because heat engines may go through a complex sequence of steps, a simplified model is often used to illustrate the principles of thermodynamics. In particular, consider a gas that expands and contracts within a cylinder with a movable piston under a…
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Because heat engines may go through a complex sequence of steps, a simplified model is often used to illustrate the principles of thermodynamics. In particular, consider a gas that expands and contracts within a cylinder with a movable piston under a…
Read More

fluid mechanics
Basic properties of fluids
…know is how the density changes when the pressure is changed by a small amount, and this is described by the compressibility of the fluid—either the isothermal compressibility, β_T, or the adiabatic compressibility, β_S, according to circumstance. When an element of fluid is compressed, the work done on it tends…
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…know is how the density changes when the pressure is changed by a small amount, and this is described by the compressibility of the fluid—either the isothermal compressibility, β_T, or the adiabatic compressibility, β_S, according to circumstance. When an element of fluid is compressed, the work done on it tends…
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seawater
Temperature distribution
…sinks to depth produces nearly isothermal conditions with depth.
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…sinks to depth produces nearly isothermal conditions with depth.
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