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There are two paths a closed system can take, to reach the same point.

But, do both paths result in the same changes to the entropy-volume?

this question got trashed in another 'syince forum' - does any one have a pointer?

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- Thread starter sirchasm
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- #1

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There are two paths a closed system can take, to reach the same point.

But, do both paths result in the same changes to the entropy-volume?

this question got trashed in another 'syince forum' - does any one have a pointer?

- #2

Mapes

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Does "reach the same point" mean "reach the same state" or "reach the same energy"? If the former, then the entropy per unit volume is changed identically; entropy and volume are state variables. If the latter, then not necessarily; adding 10 J, say, by heat will change the entropy per unit volume in a different way then adding the same amount by work.

EDIT: I should explain the difference between the two endpoints. If you're assuming the two systems are brought to the same final state, this implies that the temperatures, volumes, pressures, energies, entropies, etc. are equal. Both heat and work must be applied to both systems to satisfy this condition, but there is no requirement on the order. The final entropy and entropy per unit volume will be identical. If you're assuming the two systems are brought to the same energy only (by heating one and doing work on the other) and the pressures, volumes, etc. can be different, then the total entropy will be higher in the system that was heated.

EDIT: I should explain the difference between the two endpoints. If you're assuming the two systems are brought to the same final state, this implies that the temperatures, volumes, pressures, energies, entropies, etc. are equal. Both heat and work must be applied to both systems to satisfy this condition, but there is no requirement on the order. The final entropy and entropy per unit volume will be identical. If you're assuming the two systems are brought to the same energy only (by heating one and doing work on the other) and the pressures, volumes, etc. can be different, then the total entropy will be higher in the system that was heated.

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- #3

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Work is 'energy per unit of time', thermodynamic entropy is 'global energy over time'.

Any physical work is a derivative of energy

What about dimensionless information entropy? Does it have a volume or pressure? The units are (0,1), so what does information entropy correspond to in a gs?

- #4

Mapes

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Work is 'energy per unit of time', thermodynamic entropy is 'global energy over time'.

Any physical work is a derivative of energycontent, measurable as pressure (a deformation of volume) and temperature (a derivative of volume in pressure units); then "volume" of the physical gas is a diffusion which is positive or negative, according to entropy content;workis a measure of energy flow, and temperature is a measure of energy flow rate.

Except for "work is a measure of energy flow," this is mostly incorrect. It looks like you're just stringing technical terms together. I don't know what you're talking about.

When you say "Any physical work is a derivative of energy content," for example, does this correspond to the common definitions of work, derivative, and energy, and if so, how?

- #5

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P.S. I appreciate being corrected if I am in fact, incorrect. I don't see the point of being told "that's incorrect", and waiting around for an explanation when there isn't one.

But, I suppose I should also appreciate that someone has bothered to at least post a response of some kind.

Yo' gets what yo' can in de big worl'

- #6

Mapes

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"Any physical work is a derivative of energy content" doesn't make any sense to me. Saying that temperature is "a derivative of volume in pressure units" doesn't make any sense to me. Perhaps they're misinterpretations of something you read. But personal theories are not appropriate for this forum; that's why I asked whether you are using standard scientific definitions. Can you provide a reference for these statements?

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What does work equal, in informational terms? Or power?

Any

Even though thermodynamic work doesn't 'change' thermodynamic entropy...?

- #8

Mapes

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And what about the reference for saying temperature is "a derivative of volume in pressure units"?

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