Standard measure of distance from equilibrium for all systems

[pepperellrob]

Is there a standard way to measure how far a system is displaced from equilibrium that can be applied to all physical systems? So, for example, a ball that is kicked, a spring that is stretched, a liquid that’s heated, and a charged battery are all systems that are displaced from equilibrium. I am assuming that to quantify how far each of these is displaced from equilibrium a different measure would be used, such as the net force applied, the amount of potential energy, the temperature, or the voltage potential, and that no single measure can be applied in all cases. Is this assumption correct?

 

[BvU]

Hello @pepperellrob ,

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Interesting thought. Corny answers come to mind, like with your spring example: in the $F = -kx$ equation, the variable $x$ is a measure of how far away you are from equilibrium, litterally .

I tend to agree with your conclusion

no single measure can be applied in all cases

Now, you posted in the thermo forum. In that context (statistical mechanics) I remember the staggering sharpness of probability distributions for e.g. equilibrium pressure, entropy of a system, number of particles in a subvolume, and what have you. Perhaps the number of standard deviations away from equilibrium would be a measure in those cases. But it would be a very small measure ...

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[pepperellrob]

Thanks @BvU, that's helpful and I like your example!