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1. If work is an inexact differential as it is acknowledge and, it is actually, the greek letter delta should be use throught the article incluiding the section pressure-volume work.
2. The following wording is not accurate: "Like all work functions, PV work is path-dependent..." The word 'all' may confuse the reader. It is true at all quantitative expressions of work are path dependent if no further remarks are revealed. But, consider that all form of adiabatic work are path indepent, being this an statemente of the First Law. And please consider that by stating 'adiabatic work' you are not determining the path along the process occurs but a restrection: there may be actually many adiabatic paths conecting two given thermodynamic states all leading to the same amount of work. Thus, adiabatic work, no matter it is quantitative expression, is path independent and it can be regarded as 'work function'.
In the same way, consider that adiabatic PV work is a 'state function'. So the phase "From a thermodynamic perspective, this fact implies that PV work is not a state function." should be carefully rewritten.
3. Perphaps a subscript e should be added to external pressure. This is customary in thermodynamics literature so as to distiguish pressure ---as an equilibrium property of the thermodynamical system--- (p) from external pressure (p_e).
4. 'W= Work done on the system' may lead the reader to consider that work done by the system is different.
Etaoin Shdrlu 11:56, 7 October 2006 (UTC)
I'm not much of an expert in this field, but doesn't anyone think it's rather inconsistent to use dE = dQ - dW, where dW is defined as the work done by the system, and then use dW=-PdV, where dW is instead defined as the work done on a system? If it's convention, at least note this to the reader. 208.120.192.196 00:51, 15 April 2007 (UTC)
I do think it is a problem to use the physics sign convention in dE = dQ - dW, and then to define dw as -PdV rather than as +PdV. It seems to be wrong. Lawrence Chemistry ( talk) 13:44, 6 January 2009 (UTC)
How is thermodynamic work different from mechanical work? Joules is joules, right? Gerardw ( talk) 12:00, 17 March 2010 (UTC)
The article tells us the non-SI units of Work (thermodynamics), in L(atm) but never tells us the one in SI units. —Preceding unsigned comment added by 75.60.231.85 ( talk) 07:14, 22 November 2010 (UTC)
The result of the move request was: page moved to Work (thermodynamics). Consensus was to move, the target was less sure. This was the name that the article was at before the recent move that caused this discussion. If I got the target wrong, let me know. Vegaswikian ( talk) 00:42, 26 January 2012 (UTC)
Thermodynamical work →
Thermodynamic work – Both
wikt:thermodynamic and
wikt:thermodynamical are adjectives, but Thermodynamic is more commonly used. thermodynamic work gets 49,000 google hits, thermodynamical 1700. Request move per
WP:COMMONNAME
Nobody Ent
17:58, 19 January 2012 (UTC)
In order to be consequent, I think "thermodynamical" is better:
Or without the "-al":
But note, "mechanical work" is more common than "mechanic work". Another option:
Mixing these would be unreasonable. And "Work (physics)" can refer to any of these, therefore can't replace "Work (mechanics)" Kontos ( talk) 19:43, 19 January 2012 (UTC)
I see. Then, I think, the "Work (mechanics) - Work (electrics) - Work (thermodynamics)" pattern would be the most proper option. And, I think, it would be good if a separate article discussed the term "Work" in general under the title Work (physics). Kontos ( talk) —Preceding undated comment added 19:56, 19 January 2012 (UTC).
Of course it encompasses electrical work (a subset of it). Charges feel EM forces, and that's usually how you do work on charges or objects containg charges (with a few exceptions using the other 3 forces of nature). By contrast, it's impossible to do work through a force of physical contact except through electrical forces, since that's what "contact" is. The reason your hand doesn't go through the block when you push it up the incline, is that some charges in your hand push off other charges in the block. London forces (both repulsive and attractive) are electromagnetic. Contact forces between objects are electrical forces with shorter ranges, rather like the nuclear force is the strong force with a shorter range. But in the end (in both cases), it's the same force. We have different articles for nuclear force and strong force but we do take care to make it clear that they are the same thing with a different range-manifestation. S B H arris 20:08, 19 January 2012 (UTC)
These are all different concepts and need their own pages. In the work (physics) page you can mention that any force times distance type work qualifies, and then go through the 4 forces, with things like work (electrical) as sub/main articles. But work (thermodynamics) is not a variety of work (physics) (rather it's the other way around) so each of these articles will have to (briefly) mention the other. S B H arris 18:05, 20 January 2012 (UTC)
The section on Mechanical forms of work would fit better in Work_(physics) Nobody Ent 12:28, 11 July 2012 (UTC)
Editor Kbrose has taken it upon himself to re-write the lead according to his own-research unsourced notion of work. He has simply left the previous sources in place without offering new sources for his re-write. Nearly all of those sources were originally supplied by me, and I have a fair idea of what they say. (I have to say that some time ago, I had read less than I have read now, and I then, as Editor Kbrose now, believed that there was such a physical process as one that transferred energy as "chemical work". My subsequent further and closer reading has disabused me of my former error; largely, the version of the lead which Editor Kbrose has now produced has simply reverted to my former erroneous version.) We have no strong reason to suppose that Editor Kbrose has read any of the sources. Most concerning is his assertion of a concept of "chemical work" without offering any new source for it. All actual physically occurring chemical reactions are irreversible and and dissipative. Only the mathematical fiction of a quasi-static chemical change can be regarded as a reversible form of chemical reaction which would make it eligible as a form of theoretical though not physical work. Thus the notion of "chemical work" is wrong in physics. Editor Kbrose's adding of the notion of "chemical work" to the list of kinds of work destroys the basic logical structure of classical thermodynamics, however pleasing the notion might be to Editor Kbrose. There is no mention of "chemical work" in the usual textbook treatments of heat and work. It is true that some writers talk of it, but they are not concerned with the logical development of thermodynamics. Though Gibbs invented the idea of the chemical potential, his thermodynamics does not rely on the concept of work, because it is designed to deal with open systems, for which work is not defined. One might say that the new edit is overruling Gibbs by Kbrose's own research, unsourced. It may give some hint of how things are, that Kbrose's radical re-write was posted with not a word from him on this talk page on its radical nature. I vaguely recall previous editorial events and I do not have time or inclination to embroil myself in such things on this occasion. I will content myself here with noting that I think Kbrose's re-write of the lead is radically wrong and destructive of the version which it replaced; I have given above some reason for my view. Chjoaygame ( talk) 08:21, 12 April 2013 (UTC)
There are other faults in the destructive re-write of the initial part of the the lead by Editor Kbrose. It talks very smoothly of conjugate constraint variable pairs, but usually such pairs are properties of the system, not of the surroundings. One thinks of formulas of the form as contributions to the work, where x and X denote for example the pressure in the system and the volume of the system. The smooth talking edit gives no hint of how this accounts for isochoric work, which is not even mentioned in the re-written section, which purports to give a general account. Isochoric work must also be accounted for by processes in the surrounds. It seems that the re-written section did not trouble itself to clarify this.
Another fault in the re-written section is the apparent attribution of radiation to momentum: "other simply mechanical constraints[6], including momental[4], as in radiative transfer." This is nonsense on the face of it. It would be hard to explain this except by assuming that it means that the editor did not even bother to read the titles of the references that are cited there, let alone thinking about their meaning. I gave a reason above why I do not intend to try to remedy this destructive re-write. Chjoaygame ( talk) 13:36, 12 April 2013 (UTC)
A futher fault, indeed a reprehensible error, in the re-write is that it says that "It is customary to calculate the amount of energy transferred as work through quantities external to the system of interest." No, it is not merely customary to do so; it is obligatory. To say that it is customary is to suggest that it is only customary. The reasons why it is obligatory are so familiar and well known that I should not need to recite them here. Some recent recitations of some the reasons may be found here. Again, I leave it to others to correct this defective new version for reasons I have given above. Chjoaygame ( talk) 21:35, 12 April 2013 (UTC)
If one accepts the notion that thermodynamic work is a generalized framework over that used in mechanics then it makes no sense to arbitrarily exclude chemical processes. After all, it is in chemistry where thermodynamics has its broadest applications. The literature is full of chemical work examples, but all forms cannot always be found mentioned in all primary sources, as even primary sources tend to be opinionated one way or another depending on the mood of the period or the experience and interest of the authors. Writing about these matters in a neutral objective fashion is not easy and requires a fairly broad overview and understanding of the history of science and the various flavors or philosophies of chemical and physics teaching. In particular these subject matters and historical conflicts cannot be treated in detail in the space allotted for WP articles, nor is it desirable. In addition, the WP authors here who presently try to put their spin on these articles are poorly qualified to make these judgements. They narrowly (try to) interpret specific references, without regards to larger context and historical science evolution, or even without sufficient subject matter knowledge. Instead minute points are endlessly debated with wrong arguments and misunderstanding. Debating them is a waste of time, as nothing is ever gained. These are endless circular debates that only illustrate the incompetence of these editors. Some of them do not want to accept contemporary definitions of concepts and try to infuse these articles with their own wrong versions of physics.
The discrimination of physics vs. chemistry is anachronistic and unsustainable in modern teaching and the artificial differentiation in WP of "work (thermodynamic)" and "work (physics)" is a WP invention and wrong. Thermodynamics is physics too. If anything, the article "work (physics)" should be called "mechanical work", and the extensive treatment of mechanical work in this article should be removed, as this article should concentrate on the theoretical generalizations in thermodynamics, best the articles should be merged, as work in physics takes many forms as it does in chemistry.
RE: accusation by these authors: frankly WHO CARES? these statements are not worth responding to. It only leads to more never ending circular nonsense. It is no surprise that WP articles are shunned in education as reference or learning material and rarely does one find a reputable scientist wanting to engage with these WP editors. It is just such a pity that a work like WP cannot produce somewhat reliable science material. Ok, a couple editors here did care, thank you, for trying to bring some sense into it. Kbrose ( talk) 06:13, 16 April 2013 (UTC)
Today's edit by Kbrose removed the entire section labelled "mechanical work". As a physical chemist I agree that shaft work, spring work and elastic solid bars have little relevance to thermodynamics. I would however retain the last part about Work associated with the stretching of liquid film, since surface tension is a fundamental thermodynamic property of liquids which is of interest to chemists. May I reinsert this subsection into the article?
Also, one important category which seems absent is electrochemical work performed by (or on) cells (or batteries), which is essential to understanding redox reactions. How about a brief section on electrochemical work and the Nernst equation? Dirac66 ( talk) 23:21, 16 April 2013 (UTC)
It is unfortunate that the words work, heat, and internal energy can be confounded. The present lead of the article does that. There are historical reasons for this problem.
In the early days of thermodynamics, Clausius talked of "internal work". That concept is sometimes nowadays also referred to as "unavailable work". The Clausius usage more or less persists in this latter-day form. In present-day language, it refers to work which is supplied by a source in the surroundings of the system, but is manifest within the system at the end of the process as undifferentiated internal energy, not as remanent change in some generalized coordinates of the system such as pressure and volume exactly matching the externally supplied work. The point is that for the sound theory of thermodynamics, work is defined not by changes in the state variables of the system, but, rather, by changes in the surroundings. The idea is that for the description of process, the thermodynamic system itself is treated as a black box, avoiding mention of its internal workings and mechanisms. The mechanisms of the surroundings are considered suitable for detailed description, not just black-box summary.
An example of this problem is to be found in non-equilibrium thermodynamics. The energy associated with a transfer of matter cannot be uniquely split into heat and work components. Nevertheless there is true thermodynamic quantity associated with transfer. Some authors call it heat of transport,<Tschoegl, N.W. (2000). Fundamentals of Equilibrium and Steady-State Thermodynamics, Elsevier, Amsterdam, ISBN 0-444-50426-5, p. 209.> while others refer to work of mass transfer.<Eu, B.C. (2002). Generalized Thermodynamics. The Thermodynamics of Irreversible Processes and Generalized Hydrodynamics, Kluwer Academic Publishers, Dordrecht, ISBN 1-4020-0788-4, p. 26.> The latter author is an unashamed user of many of Clausius' definitions, and an inventor of a new term for his own purposes "calortropy".
My view is that this problem is best dealt with in these pages by consistent use of the term internal energy to refer to the energy associated with transfer of matter.
Eu also speaks of as "work" what I think would be better referred to as energy of process when Eu is talking about chemical reactions, and in other contexts. As I have mentioned just above, Eu is a little idiosyncratic in his terminology. Since natural chemical reactions are always irreversible, it is likely to confuse readers to speak of its energy as "work". Work in the surroundings is often considered by thermodynamic convention as able to be performed reversibly, contrary to nature.
Thermodynamic work supplied by the surroundings is naturally not stored in the system entirely as available work, the so-called "work of the task". Thermodynamic work supplied by the surroundings is in natural processes partly converted into internal energy in the system that cannot be recovered without special changes in the surroundings. That part is Clausius' "internal work". In present-day terminology, its storage is described by the state variable internal energy, and in present-day terminology is it not stored as work in the system. Work is a process variable.
Some people like to use the term generalized to refer to kinds of thermodynamic work. This can be confusing and harmful for those not at home with the specialized jargon. The problem partly arises because of the term 'generalized work variable'. The base case for thermodynamic work is pressure-volume work. An electric field imposed from outside the system also does work on the system, and this leads it to be termed a 'generalized work variable'. Then the drift of terminology goes to any extensive variable that has a conjugate intensive variable, such as mole number, and all are lumped as "generalized work variables". An easy slip down a bad path.
I think the best and clearest way for Wikipedia thermodynamics articles is to stay with the simplest definition of work as supplied by a source in the surroundings, which may be a reversible source. Heat is transferred without work or matter transfer. Other transfers of internal energy are transfers of internal energy.
For statistical mechanics, thermodynamic work can be supplied by externally imposed changes in the set-up of the system, such as changes in volume or length, that are manifest as remanent changes in the energy levels of the system. Thermodynamic work can also be supplied by rapid motion of the system that is eventually left with its original volume or length and original energy levels unchanged, though the occupation numbers were changed permanently during the process. Clausius would call this 'internal work'. Clausius would also say that it heated the system, but it is not heat transfer as defined in present-day thermodynamics. Chjoaygame ( talk) 18:29, 1 April 2014 (UTC)
I would like to propose a change to the present article.
I think the definition of "work" that heads the present article is more safely regarded as a definition of 'generalized work'. It reads:
My reason is that the concept of mechanical work in physics is fundamental and primitive, presupposed for thermodynamics as expounded since 1909. It is potentially confusing to replace it with a concept of 'generalized work'. I think it safer to say distinctly and explicitly that 'generalized work' is a generalization of work.
It is foundational to the exposition of thermodynamics that work can be said to done by a system or working substance and that the amount is counted in the surroundings as delivered macroscopically without dissipation. This is more of a theoretical postulate than a description of practical experience. But it is a postulate that is needed for a convenient theoretical development. I don't think I can mount a better argument than this.
In particular, so-called "chemical work" is, I propose, best regarded as a kind of generalized work. Physically it goes on at the molecular level, not directly as macroscopically observable mechanical work such as is envisaged in the foundational exposition. I regard that as essential to the nature of chemical work. Something that happens at the molecular level is vulnerable to the vagaries of the second law.
My reference this is, I think, sufficient. According to Prigogine & Defay, the system's chemical reactions themselves (except for the special limiting case in which in they are driven through devices in the surroundings so as to occur along a line of thermodynamic equilibrium) are always irreversible and do not directly interact with the surroundings of the system. [1]
Chjoaygame ( talk) 01:42, 2 September 2015 (UTC)
No reply?
It is evident that people like to use the concept of generalized work, to include all state variables other than temperature regarded as measuring quasi-static heat transfer. I would like to suggest that generalized work here be called generalized work, while work is called work, and defined as proposed, for example, by Haase, and by Münster, as cited here below at response 2. Chjoaygame ( talk) 12:17, 5 September 2015 (UTC)
I have checked the reference cited for the claim that radiative transfer can be called work. The reference says that radiation can at times need to be considered as a component of a system, but does not suggest that radiative transfer can be called work. Accordingly I have removed radiation from the list of forms of work. It was a mistake to put it there in the first place.
Chjoaygame (
talk)
08:28, 7 September 2015 (UTC)
This undo, by Editor Melmann was on the whole deleterious. It seems to have relied on an automated algorithm that demanded citation of reliable sourcing, but did not otherwise evaluate the edits that it undid.
The undone edits had merit. In particular, they removed a demand for reversibility. For the formulas involved, indeed reversibility is NOT a requirement. Removal of the demand was right. Also, they distinctly improved the wording that described the formulas.
It would be good if good quality (not mediocre) reliable sources were cited for the edits. Their current absence is undesirable, but, I think, not reason enough to undo them.
I am undoing the undo. Chjoaygame ( talk) 12:11, 3 September 2015 (UTC)
Two days ago editor Chjoaygame deleted the following as a "faulty IP edit": Work is said to be done by a system if , its sole effect on the things external to the sourroundings is reduced to raising of the weight.
I agree that the deleted edit as written is fundamentally faulty (in addition to linguistically faulty) because there are other types of work besides raising weights, such as electrical work and many other types mentioned in the article.
However this edit reminds me of a more correct statement, and a quick Google search yielded the version here, where the definition of work is written: Work is done by a system on the surroundings if the sole effect on everything external to the system could have been raising a weight. As briefly explained further down on the Learnthermo website in the section Ch 4, Lesson A, Page 2 - The Thermodynamic Definition of Work, the key words are could have been. I also remember reading the key words somewhere else as can be (completely) converted into; for example the electrical work of charging a battery can be completely converted into the work of raising a weight by an electric motor. This distinguishes work from heat which by the Second Law can only be partially converted into the work of raising a weight.
This idea seems to be missing from the article, and I would like to suggest that the article should include a rewritten version including the idea of potential (and not necessarily actual) conversion to the raising of a weight, as well as a more authoritative source if possible. Do others agree? Dirac66 ( talk) 01:07, 4 September 2015 (UTC)
Editor Dirac66 raises an important matter.
He is concerned, as I read it, about a distinction between work defined rather directly and simply, and work defined more indirectly and I would say more complicatedly. By direct and simple I mean that the system must deliver its work as a macroscopic force felt immediately by the surroundings. What happens further in the surroundings can be analyzed further when one has sorted out the concepts needed to describe the adventures of the system. A question may arise of whether the flow of electrons is a transfer of matter. I am inclined, at least for the present, to think that to escape being considered as a transfer of matter it should result in no net transfer of charge.
I am not sure where the proposal to define in terms of raising a weight comes from. I have read it in some texts that I find clever and self-confident but not too convincing. I think it is an attempt to create concreteness, but that it goes too far.
The questions arise in considering the adventures of the transferred energy in question as it occurs in the surroundings. I distinguish this from its adventures in the system. He emphasizes the phrase could have been.
Perhaps this is a way of talking about a distinction between work in the direct and simple sense, and what may be called 'generalized work'.
Editor Dirac66 writes "for example the electrical work of charging a battery can be completely converted into the work of raising a weight by an electric motor." This does not explicitly distinguish the system from the surroundings. It is not clear to me whether the battery or the motor is in the system or in the surroundings.
There may be a problem with defining things in terms of "the raising of a weight". It presupposes gravity acting on the weight. It may not be easy to arrange that the system be exempt from gravity while the surroundings have it. We have recently had some questions about whether the second law can be stated for systems in the presence of an external field. Part of the problem is the desire to jump in theory to continuously distributed inhomogeneous systems before homogeneous systems have been settled. I have carefully read the committee report, written by Alberty, cited by a certain redoubtable editor. I have further carefully read a major text by Alberty and others. My conclusion is that our redoubtable editor is not rightly reading Alberty.
I am not too sure about an authoritative source. There are very many more or less reliable sources. If there are significant differences among them then the question of Wikipedia point-of-view multiplicity may arise. Which, if any, is more authoritative? I think we ought to try to analyze and distill the best, at least as a first approach.
I think it most important that the more concrete and simple definition be given a good run, because of its fundamental place in the basic logic of the subject. Charging a battery is a chemical process and according to Prigogine and Defay, as I read them, is not in general reversible.
Another fundamental point that I think needs a good run is the distinction between the total energy of a system and its internal energy. The total energy is very often representable as the sum of three terms, the internal energy of the system, its kinetic energy as a whole, and its potential energy as a whole, obviously with respect to some externally imposed force field.
I think it important that the basic concepts be defined strictly in macroscopic terms, not relying on continuous field pictures of the system's internal content, expressed in internally spatial differential equations. The internal spatial differential equation approach should be derived from the macroscopic approach. The internal spatial differential equation approach is not good for an introduction in any case.
I suppose that further discussion may arise. Chjoaygame ( talk) 05:30, 4 September 2015 (UTC)
Having babbled airily about basic foundations, perhaps I ought to say more explicitly what I intend by that.
First we settle the system with respect to its surroundings, as to its velocity and attendant kinetic energy as a whole, and as to its position and potential energy as a whole. The remainder of its total energy is the internal energy.
Next, the internal energy is determined for a closed system, that is to say, for which matter transfer is not allowed by its walls. We further require processes that do not involve transfer of energy as heat. The system has adiabatic walls as its only dealing. All that is left are transfers as work. There is very strong opinion here that this is the foundational reasoning. This is why I think work should be treated very carefully.
Next we allow also transfer as heat, still forbidding transfer of matter. Thus we determine the mechanical equivalent of heat, and we use only mechanical units.
Next we allow also transfer of matter, through walls spatially and otherwise separate from those that allow the transfer as heat and work but not matter. We forbid heat and work transfers, and allowing transfer of matter we have only ΔU1 + ΔU2 = 0. Now it's time to be very careful indeed about our reference states, and we can find the amount of energy transferred in company with matter transfer, not uniquely resolvable into heat and work transfers.
As for the general setting. It doesn't matter in what order are the postulates are listed. It's all the postulates at once, or go back to the drawing board. One of the postulates in the established view is conservation of energy. The existence of adiabatic walls is also foundationally postulated in the established view. But the sequence in which the postulates are called upon in argumentative presentation does matter and is open to opinion while still not trying to alter the basic postulates. Chjoaygame ( talk) 08:13, 4 September 2015 (UTC)
Thank you for your response.
Denbigh and Kestin ring bells for me, but I need to go to the library to get them.
As a very loose and vague statement, open to immediate change or denial, perhaps one might say that what happens in the surroundings is less scrutinized than what happens in the system. Very loosely thinking, perhaps one might say that work done on the surroundings is allowed to be done on ideal work transducers, as a matter of convention? This would create problems for some statements of the second law, I think? I would think it a mistake to allow the battery as an ideal work transducer because it happens by chemical reactions, which are irreversible, because they change many disorganized single ions or molecules, not obviously macroscopic items.
Haase [1] has a section on work on pages 19–24. Amongst other things he says that P dV is not an exact differential, which I think may show that I was wrong to allow a recent edit that removed a caveat that required reversibility. Haase in that section cites only Guggenheim and Callen. He writes as follows on page 20.
No explicit mention of gravity there. Perhaps that is a weakness in his presentation? He explicitly restricts the section to refer only to closed systems.
More to think about here. Need some time. Chjoaygame ( talk) 01:48, 5 September 2015 (UTC)
Not much luck right now in library. Denbigh: two editions out on loan, one in Engineering Store, one in General Store. Kestin: in Engineering Store. All take days or weeks to get. Andrews and Saad not held. Chjoaygame ( talk) 04:36, 5 September 2015 (UTC)
An extract from the present article:
This may partly address our present concerns.
An extract from Callen:
So I was wrong to let that edit through. I will shortly fix it.
Münster has little to say about work immediately relevant to the weight-lifting thing. He writes:
in agreement with Callen. Chjoaygame ( talk) 09:03, 5 September 2015 (UTC)
On page 31, Silbey, Alberty, & Bawendi write "Work is often conveniently measured by the lifting or falling of masses." Chjoaygame ( talk) 23:16, 5 September 2015 (UTC)
Thank you for this reply. Looking in the article, I see quite a lot of text. Of that, I have contributed some, and perhaps some of that needs correction.
At the end of the article's text is the following:
The lead starts as follows:
Perhaps these points have more to do with the section above on this talk page, headed work or generalized 'work', and might be further discussed there. The present section is about using lifting a weight to put work in a nutshell, as you are proposing, and I am happy about. Chjoaygame ( talk) 05:45, 6 September 2015 (UTC)
The library responded quickly. Here follow some findings.
Denbigh 1st edition reprinted 1957
Page 14:
The wording of the last, just previous, sentence is slightly different in the 4th edition (1981/reprint 1993).
Kestin 1966
Chapter 4, pp. 110–148.
[Discussion of the difference between raising and lowering of a weight, in terms of what could be so.]
[Discussion of reversible, irreversible, and quasistatic processes.]
It seems to me that Kestin is here talking about 'work in reversible and quasistatic processes', not the same as the phrase I proposed, 'generalized work'. I think our present article is also talking about work in reversible and quasistatic processes.
This last remark is not reflected systematically in the present article. Chjoaygame ( talk) 00:11, 9 September 2015 (UTC)
Perhaps my following the references has sidetracked too much from Editor Dirac66's proposal to put in a section about potential to raise a weight. Perhaps I should repeat here that I am happy with his proposal. Chjoaygame ( talk) 08:32, 15 September 2015 (UTC)
I have undone a good faith edit. The edit is over-explanatory. If the work is done on the system, it is counted as work, even if it is frictional. Some of the frictional work may be done on the surroundings, and become internal energy of the surroundings, and then pass to the system as heat; that is energy passing to the system as heat, not as work done on the system. The system does not do work as friction on the surroundings. Chjoaygame ( talk) 23:39, 2 January 2016 (UTC)
Just a small discrepancy I noticed while having to correct two links contained in the Enthalpy wiki article to the section of this page: Work_(thermodynamics)#Pressure–volume_work. The issue was that they linked to Work_(thermodynamics)#Pressure-volume_work (with a hyphen, not an en dash) instead of Work_(thermodynamics)#Pressure–volume_work (with an en dash, not a hyphen). In this article ( Work_(thermodynamics)), there are 11 cases of "Pressure–volume work" with an en dash, and 2 cases of "Pressure-volume work" with a hyphen. I imagine that it is easy to make the mistake of not using an en dash when linking to Work_(thermodynamics)#Pressure–volume_work, like what happened in the Enthalpy article. Further, according to this article: https://www.grammarly.com/blog/en-dash/ , en dashes should only be used in complex compound adjectives, not regular compound adjectives. This article: https://www.dailywritingtips.com/en-dashes-clarify-compound-phrasal-adjectives/ seems to agree. And take a look at Bose–Einstein_condensate. It contains mostly en dashes, but some of the sources at the bottom also contain hyphens (use your browser's search function to search for – or -). https://english.stackexchange.com/questions/2116/when-should-i-use-an-em-dash-an-en-dash-and-a-hyphen seems to agree as well (feel free to check this source).
Now, in the case of "Pressure–volume work" or "Bose–Einstein condensate", the en dash is being used in place of an "and". According to wiki article Dash (as of March 30, 2019):
The French and Indian War (1754–1763) was fought in western Pennsylvania and along the present US–Canada border (Edwards, pp. 81–101).
Notice how it says [Not in citation given]. I wasn't able to access the source to check if the en dash can be used instead of "and".
Given the above, it seems as though that the hyphen should be used instead of the en dash. Unless there's better evidence to the contrary. -- 174.57.210.161 ( talk) 04:35, 30 March 2019 (UTC)
This dispute at talk:Heat puts under question whether this article is named correctly. TL;DR: the present article restricts itself to reversible work. How do thermodynamics textbooks describe Joule’s paddles (a.k.a. “isochoric work”)? Incnis Mrsi ( talk) 15:06, 28 July 2019 (UTC)
A tag has been posted, asking "according to whom?", about the sentence "When it is done isochorically, and no matter is transferred, such an energy transfer is regarded as a heat transfer into the system of interest."
The currently used definition of heat transfer is that it is transfer of energy to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter.
The energy transfer in this case is supplied by externally applied work, defined as work in the surroundings, that does not act through immediate direct effect on the state variables of the system that define thermodynamic work for the system, for example volume, but, rather, acts on the system through friction. The energy transfer is not by transfer of matter. Chjoaygame ( talk) 11:28, 29 July 2019 (UTC)
The definition of Heat in the respective wikipedia aricle has the answer. Any transfer of energy between 2 systems occur as heat. The Joule's paddle example is the same. If Incnis Mrsi understands the Joule's paddle process, he/she must have had understood the question's answer, and there would have been no need of this according to whom?. So, I would suugest him/her to go through it carefully. Lichinsol ( talk) 14:29, 29 July 2019 (UTC)
If nobody objects, then I replace “… regarded as a heat transfer into…” with “… regarded as transformation to heat input for…”. Incnis Mrsi ( talk) 14:58, 29 July 2019 (UTC)
Yes, as Chjoaygame says near the end of the above discussion, there is a difference on Wikipedia between Wikilinking and Citing a reliable source. Here, two plus years after the above discussion, no one has yet answered the question "According to whom" by providing a reliable source. Wikilinks help to explain words which may be unfamiliar to some readers, but Wikipedia policy is that non-obvious and especially controversial statements are supposed to be supported by reliable sources. Reading quickly, we seem to have several conflicting opinions in the above discussion. Can someone please provide a reliable external source for the claim in the intro that isochoric Joule heating without matter transfer is just heat transfer. One might argue that it is electrical work used to heat the system. Is there a textbook or review article that clearly says one or the other? Dirac66 ( talk) 00:18, 10 October 2021 (UTC)
I have undone this good faith edit.
The edit has the merit of brevity. But it is so brief that a newcomer would get inadequate guidance to its meaning. Chjoaygame ( talk) 00:17, 24 October 2020 (UTC)
Thermodynamic work can be distinguished from work done by agents or factors in the surroundings. For a closed system, the latter can be conceptually split into work that changes only the 'work-like' state variables of the system, for example P–V work, and what engineers call 'shaft work', used in Joule's paddle-wheel experiment, also called 'isochoric' work by some physicists. Such 'shaft work' or 'isochoric work' appears in the system's state variable increments as S–T energy. Chjoaygame ( talk) 02:20, 6 December 2020 (UTC)
"Mode of..." is useless overhead to something that is meant to be terse. How about "Reversible energy transfer between a system and its surroundings"? VQuakr ( talk) 21:21, 7 January 2021 (UTC)
Quoting: "No short description is a complete discussion of the topic."
Quoting: It is by its nature terse.
Quoting: Again, 2nd law doesn't preclude truly reversible processes, which do actually occur on a micro scale - "reversible" is fully accurate.
Quoting: 2nd law precludes the entropy of a closed system from decreasing, but does not prevent it from remaining constant.
Quoting: Where at WP:SHORTDES does it say we shouldn't use technical terms?
A short title is just a method of cataloging subjects, it does not have to, nor can it possibly, define terms with any kind of detail. This hackling is just more of the same shortsightedness that doesn't see the forest for the trees. kbrose ( talk) 14:39, 13 January 2021 (UTC)
I thank you for your interest. Nevertheless, I think 'distinguished' is the right word for the job. 'Distinct' doesn't have the same depth of meaning. The point is more than distinctness; it is special distinctness. An example of the difference is in group theory. The identity element (0 for additive groups) is more than just distinct. Every group element is distinct. But 0 is special, and it is customary to express this by saying that it is distinguished. I think this custom is suitable here. For example, isobaric processes constitute a distinct class of processes, but I think they are not distinguished in quite the same way as are work, heat, and matter transfer, which are distinguished in the notation for changes of internal energy.
I agree that 'measureable' is better.
I thought about 'these' and 'those', and preferred 'those'. Chjoaygame ( talk) 21:23, 13 April 2023 (UTC)
@ Dirac66: Hi, Dirac66. I would be glad of a reply to the above. Chjoaygame ( talk) 08:22, 15 April 2023 (UTC)
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1. If work is an inexact differential as it is acknowledge and, it is actually, the greek letter delta should be use throught the article incluiding the section pressure-volume work.
2. The following wording is not accurate: "Like all work functions, PV work is path-dependent..." The word 'all' may confuse the reader. It is true at all quantitative expressions of work are path dependent if no further remarks are revealed. But, consider that all form of adiabatic work are path indepent, being this an statemente of the First Law. And please consider that by stating 'adiabatic work' you are not determining the path along the process occurs but a restrection: there may be actually many adiabatic paths conecting two given thermodynamic states all leading to the same amount of work. Thus, adiabatic work, no matter it is quantitative expression, is path independent and it can be regarded as 'work function'.
In the same way, consider that adiabatic PV work is a 'state function'. So the phase "From a thermodynamic perspective, this fact implies that PV work is not a state function." should be carefully rewritten.
3. Perphaps a subscript e should be added to external pressure. This is customary in thermodynamics literature so as to distiguish pressure ---as an equilibrium property of the thermodynamical system--- (p) from external pressure (p_e).
4. 'W= Work done on the system' may lead the reader to consider that work done by the system is different.
Etaoin Shdrlu 11:56, 7 October 2006 (UTC)
I'm not much of an expert in this field, but doesn't anyone think it's rather inconsistent to use dE = dQ - dW, where dW is defined as the work done by the system, and then use dW=-PdV, where dW is instead defined as the work done on a system? If it's convention, at least note this to the reader. 208.120.192.196 00:51, 15 April 2007 (UTC)
I do think it is a problem to use the physics sign convention in dE = dQ - dW, and then to define dw as -PdV rather than as +PdV. It seems to be wrong. Lawrence Chemistry ( talk) 13:44, 6 January 2009 (UTC)
How is thermodynamic work different from mechanical work? Joules is joules, right? Gerardw ( talk) 12:00, 17 March 2010 (UTC)
The article tells us the non-SI units of Work (thermodynamics), in L(atm) but never tells us the one in SI units. —Preceding unsigned comment added by 75.60.231.85 ( talk) 07:14, 22 November 2010 (UTC)
The result of the move request was: page moved to Work (thermodynamics). Consensus was to move, the target was less sure. This was the name that the article was at before the recent move that caused this discussion. If I got the target wrong, let me know. Vegaswikian ( talk) 00:42, 26 January 2012 (UTC)
Thermodynamical work →
Thermodynamic work – Both
wikt:thermodynamic and
wikt:thermodynamical are adjectives, but Thermodynamic is more commonly used. thermodynamic work gets 49,000 google hits, thermodynamical 1700. Request move per
WP:COMMONNAME
Nobody Ent
17:58, 19 January 2012 (UTC)
In order to be consequent, I think "thermodynamical" is better:
Or without the "-al":
But note, "mechanical work" is more common than "mechanic work". Another option:
Mixing these would be unreasonable. And "Work (physics)" can refer to any of these, therefore can't replace "Work (mechanics)" Kontos ( talk) 19:43, 19 January 2012 (UTC)
I see. Then, I think, the "Work (mechanics) - Work (electrics) - Work (thermodynamics)" pattern would be the most proper option. And, I think, it would be good if a separate article discussed the term "Work" in general under the title Work (physics). Kontos ( talk) —Preceding undated comment added 19:56, 19 January 2012 (UTC).
Of course it encompasses electrical work (a subset of it). Charges feel EM forces, and that's usually how you do work on charges or objects containg charges (with a few exceptions using the other 3 forces of nature). By contrast, it's impossible to do work through a force of physical contact except through electrical forces, since that's what "contact" is. The reason your hand doesn't go through the block when you push it up the incline, is that some charges in your hand push off other charges in the block. London forces (both repulsive and attractive) are electromagnetic. Contact forces between objects are electrical forces with shorter ranges, rather like the nuclear force is the strong force with a shorter range. But in the end (in both cases), it's the same force. We have different articles for nuclear force and strong force but we do take care to make it clear that they are the same thing with a different range-manifestation. S B H arris 20:08, 19 January 2012 (UTC)
These are all different concepts and need their own pages. In the work (physics) page you can mention that any force times distance type work qualifies, and then go through the 4 forces, with things like work (electrical) as sub/main articles. But work (thermodynamics) is not a variety of work (physics) (rather it's the other way around) so each of these articles will have to (briefly) mention the other. S B H arris 18:05, 20 January 2012 (UTC)
The section on Mechanical forms of work would fit better in Work_(physics) Nobody Ent 12:28, 11 July 2012 (UTC)
Editor Kbrose has taken it upon himself to re-write the lead according to his own-research unsourced notion of work. He has simply left the previous sources in place without offering new sources for his re-write. Nearly all of those sources were originally supplied by me, and I have a fair idea of what they say. (I have to say that some time ago, I had read less than I have read now, and I then, as Editor Kbrose now, believed that there was such a physical process as one that transferred energy as "chemical work". My subsequent further and closer reading has disabused me of my former error; largely, the version of the lead which Editor Kbrose has now produced has simply reverted to my former erroneous version.) We have no strong reason to suppose that Editor Kbrose has read any of the sources. Most concerning is his assertion of a concept of "chemical work" without offering any new source for it. All actual physically occurring chemical reactions are irreversible and and dissipative. Only the mathematical fiction of a quasi-static chemical change can be regarded as a reversible form of chemical reaction which would make it eligible as a form of theoretical though not physical work. Thus the notion of "chemical work" is wrong in physics. Editor Kbrose's adding of the notion of "chemical work" to the list of kinds of work destroys the basic logical structure of classical thermodynamics, however pleasing the notion might be to Editor Kbrose. There is no mention of "chemical work" in the usual textbook treatments of heat and work. It is true that some writers talk of it, but they are not concerned with the logical development of thermodynamics. Though Gibbs invented the idea of the chemical potential, his thermodynamics does not rely on the concept of work, because it is designed to deal with open systems, for which work is not defined. One might say that the new edit is overruling Gibbs by Kbrose's own research, unsourced. It may give some hint of how things are, that Kbrose's radical re-write was posted with not a word from him on this talk page on its radical nature. I vaguely recall previous editorial events and I do not have time or inclination to embroil myself in such things on this occasion. I will content myself here with noting that I think Kbrose's re-write of the lead is radically wrong and destructive of the version which it replaced; I have given above some reason for my view. Chjoaygame ( talk) 08:21, 12 April 2013 (UTC)
There are other faults in the destructive re-write of the initial part of the the lead by Editor Kbrose. It talks very smoothly of conjugate constraint variable pairs, but usually such pairs are properties of the system, not of the surroundings. One thinks of formulas of the form as contributions to the work, where x and X denote for example the pressure in the system and the volume of the system. The smooth talking edit gives no hint of how this accounts for isochoric work, which is not even mentioned in the re-written section, which purports to give a general account. Isochoric work must also be accounted for by processes in the surrounds. It seems that the re-written section did not trouble itself to clarify this.
Another fault in the re-written section is the apparent attribution of radiation to momentum: "other simply mechanical constraints[6], including momental[4], as in radiative transfer." This is nonsense on the face of it. It would be hard to explain this except by assuming that it means that the editor did not even bother to read the titles of the references that are cited there, let alone thinking about their meaning. I gave a reason above why I do not intend to try to remedy this destructive re-write. Chjoaygame ( talk) 13:36, 12 April 2013 (UTC)
A futher fault, indeed a reprehensible error, in the re-write is that it says that "It is customary to calculate the amount of energy transferred as work through quantities external to the system of interest." No, it is not merely customary to do so; it is obligatory. To say that it is customary is to suggest that it is only customary. The reasons why it is obligatory are so familiar and well known that I should not need to recite them here. Some recent recitations of some the reasons may be found here. Again, I leave it to others to correct this defective new version for reasons I have given above. Chjoaygame ( talk) 21:35, 12 April 2013 (UTC)
If one accepts the notion that thermodynamic work is a generalized framework over that used in mechanics then it makes no sense to arbitrarily exclude chemical processes. After all, it is in chemistry where thermodynamics has its broadest applications. The literature is full of chemical work examples, but all forms cannot always be found mentioned in all primary sources, as even primary sources tend to be opinionated one way or another depending on the mood of the period or the experience and interest of the authors. Writing about these matters in a neutral objective fashion is not easy and requires a fairly broad overview and understanding of the history of science and the various flavors or philosophies of chemical and physics teaching. In particular these subject matters and historical conflicts cannot be treated in detail in the space allotted for WP articles, nor is it desirable. In addition, the WP authors here who presently try to put their spin on these articles are poorly qualified to make these judgements. They narrowly (try to) interpret specific references, without regards to larger context and historical science evolution, or even without sufficient subject matter knowledge. Instead minute points are endlessly debated with wrong arguments and misunderstanding. Debating them is a waste of time, as nothing is ever gained. These are endless circular debates that only illustrate the incompetence of these editors. Some of them do not want to accept contemporary definitions of concepts and try to infuse these articles with their own wrong versions of physics.
The discrimination of physics vs. chemistry is anachronistic and unsustainable in modern teaching and the artificial differentiation in WP of "work (thermodynamic)" and "work (physics)" is a WP invention and wrong. Thermodynamics is physics too. If anything, the article "work (physics)" should be called "mechanical work", and the extensive treatment of mechanical work in this article should be removed, as this article should concentrate on the theoretical generalizations in thermodynamics, best the articles should be merged, as work in physics takes many forms as it does in chemistry.
RE: accusation by these authors: frankly WHO CARES? these statements are not worth responding to. It only leads to more never ending circular nonsense. It is no surprise that WP articles are shunned in education as reference or learning material and rarely does one find a reputable scientist wanting to engage with these WP editors. It is just such a pity that a work like WP cannot produce somewhat reliable science material. Ok, a couple editors here did care, thank you, for trying to bring some sense into it. Kbrose ( talk) 06:13, 16 April 2013 (UTC)
Today's edit by Kbrose removed the entire section labelled "mechanical work". As a physical chemist I agree that shaft work, spring work and elastic solid bars have little relevance to thermodynamics. I would however retain the last part about Work associated with the stretching of liquid film, since surface tension is a fundamental thermodynamic property of liquids which is of interest to chemists. May I reinsert this subsection into the article?
Also, one important category which seems absent is electrochemical work performed by (or on) cells (or batteries), which is essential to understanding redox reactions. How about a brief section on electrochemical work and the Nernst equation? Dirac66 ( talk) 23:21, 16 April 2013 (UTC)
It is unfortunate that the words work, heat, and internal energy can be confounded. The present lead of the article does that. There are historical reasons for this problem.
In the early days of thermodynamics, Clausius talked of "internal work". That concept is sometimes nowadays also referred to as "unavailable work". The Clausius usage more or less persists in this latter-day form. In present-day language, it refers to work which is supplied by a source in the surroundings of the system, but is manifest within the system at the end of the process as undifferentiated internal energy, not as remanent change in some generalized coordinates of the system such as pressure and volume exactly matching the externally supplied work. The point is that for the sound theory of thermodynamics, work is defined not by changes in the state variables of the system, but, rather, by changes in the surroundings. The idea is that for the description of process, the thermodynamic system itself is treated as a black box, avoiding mention of its internal workings and mechanisms. The mechanisms of the surroundings are considered suitable for detailed description, not just black-box summary.
An example of this problem is to be found in non-equilibrium thermodynamics. The energy associated with a transfer of matter cannot be uniquely split into heat and work components. Nevertheless there is true thermodynamic quantity associated with transfer. Some authors call it heat of transport,<Tschoegl, N.W. (2000). Fundamentals of Equilibrium and Steady-State Thermodynamics, Elsevier, Amsterdam, ISBN 0-444-50426-5, p. 209.> while others refer to work of mass transfer.<Eu, B.C. (2002). Generalized Thermodynamics. The Thermodynamics of Irreversible Processes and Generalized Hydrodynamics, Kluwer Academic Publishers, Dordrecht, ISBN 1-4020-0788-4, p. 26.> The latter author is an unashamed user of many of Clausius' definitions, and an inventor of a new term for his own purposes "calortropy".
My view is that this problem is best dealt with in these pages by consistent use of the term internal energy to refer to the energy associated with transfer of matter.
Eu also speaks of as "work" what I think would be better referred to as energy of process when Eu is talking about chemical reactions, and in other contexts. As I have mentioned just above, Eu is a little idiosyncratic in his terminology. Since natural chemical reactions are always irreversible, it is likely to confuse readers to speak of its energy as "work". Work in the surroundings is often considered by thermodynamic convention as able to be performed reversibly, contrary to nature.
Thermodynamic work supplied by the surroundings is naturally not stored in the system entirely as available work, the so-called "work of the task". Thermodynamic work supplied by the surroundings is in natural processes partly converted into internal energy in the system that cannot be recovered without special changes in the surroundings. That part is Clausius' "internal work". In present-day terminology, its storage is described by the state variable internal energy, and in present-day terminology is it not stored as work in the system. Work is a process variable.
Some people like to use the term generalized to refer to kinds of thermodynamic work. This can be confusing and harmful for those not at home with the specialized jargon. The problem partly arises because of the term 'generalized work variable'. The base case for thermodynamic work is pressure-volume work. An electric field imposed from outside the system also does work on the system, and this leads it to be termed a 'generalized work variable'. Then the drift of terminology goes to any extensive variable that has a conjugate intensive variable, such as mole number, and all are lumped as "generalized work variables". An easy slip down a bad path.
I think the best and clearest way for Wikipedia thermodynamics articles is to stay with the simplest definition of work as supplied by a source in the surroundings, which may be a reversible source. Heat is transferred without work or matter transfer. Other transfers of internal energy are transfers of internal energy.
For statistical mechanics, thermodynamic work can be supplied by externally imposed changes in the set-up of the system, such as changes in volume or length, that are manifest as remanent changes in the energy levels of the system. Thermodynamic work can also be supplied by rapid motion of the system that is eventually left with its original volume or length and original energy levels unchanged, though the occupation numbers were changed permanently during the process. Clausius would call this 'internal work'. Clausius would also say that it heated the system, but it is not heat transfer as defined in present-day thermodynamics. Chjoaygame ( talk) 18:29, 1 April 2014 (UTC)
I would like to propose a change to the present article.
I think the definition of "work" that heads the present article is more safely regarded as a definition of 'generalized work'. It reads:
My reason is that the concept of mechanical work in physics is fundamental and primitive, presupposed for thermodynamics as expounded since 1909. It is potentially confusing to replace it with a concept of 'generalized work'. I think it safer to say distinctly and explicitly that 'generalized work' is a generalization of work.
It is foundational to the exposition of thermodynamics that work can be said to done by a system or working substance and that the amount is counted in the surroundings as delivered macroscopically without dissipation. This is more of a theoretical postulate than a description of practical experience. But it is a postulate that is needed for a convenient theoretical development. I don't think I can mount a better argument than this.
In particular, so-called "chemical work" is, I propose, best regarded as a kind of generalized work. Physically it goes on at the molecular level, not directly as macroscopically observable mechanical work such as is envisaged in the foundational exposition. I regard that as essential to the nature of chemical work. Something that happens at the molecular level is vulnerable to the vagaries of the second law.
My reference this is, I think, sufficient. According to Prigogine & Defay, the system's chemical reactions themselves (except for the special limiting case in which in they are driven through devices in the surroundings so as to occur along a line of thermodynamic equilibrium) are always irreversible and do not directly interact with the surroundings of the system. [1]
Chjoaygame ( talk) 01:42, 2 September 2015 (UTC)
No reply?
It is evident that people like to use the concept of generalized work, to include all state variables other than temperature regarded as measuring quasi-static heat transfer. I would like to suggest that generalized work here be called generalized work, while work is called work, and defined as proposed, for example, by Haase, and by Münster, as cited here below at response 2. Chjoaygame ( talk) 12:17, 5 September 2015 (UTC)
I have checked the reference cited for the claim that radiative transfer can be called work. The reference says that radiation can at times need to be considered as a component of a system, but does not suggest that radiative transfer can be called work. Accordingly I have removed radiation from the list of forms of work. It was a mistake to put it there in the first place.
Chjoaygame (
talk)
08:28, 7 September 2015 (UTC)
This undo, by Editor Melmann was on the whole deleterious. It seems to have relied on an automated algorithm that demanded citation of reliable sourcing, but did not otherwise evaluate the edits that it undid.
The undone edits had merit. In particular, they removed a demand for reversibility. For the formulas involved, indeed reversibility is NOT a requirement. Removal of the demand was right. Also, they distinctly improved the wording that described the formulas.
It would be good if good quality (not mediocre) reliable sources were cited for the edits. Their current absence is undesirable, but, I think, not reason enough to undo them.
I am undoing the undo. Chjoaygame ( talk) 12:11, 3 September 2015 (UTC)
Two days ago editor Chjoaygame deleted the following as a "faulty IP edit": Work is said to be done by a system if , its sole effect on the things external to the sourroundings is reduced to raising of the weight.
I agree that the deleted edit as written is fundamentally faulty (in addition to linguistically faulty) because there are other types of work besides raising weights, such as electrical work and many other types mentioned in the article.
However this edit reminds me of a more correct statement, and a quick Google search yielded the version here, where the definition of work is written: Work is done by a system on the surroundings if the sole effect on everything external to the system could have been raising a weight. As briefly explained further down on the Learnthermo website in the section Ch 4, Lesson A, Page 2 - The Thermodynamic Definition of Work, the key words are could have been. I also remember reading the key words somewhere else as can be (completely) converted into; for example the electrical work of charging a battery can be completely converted into the work of raising a weight by an electric motor. This distinguishes work from heat which by the Second Law can only be partially converted into the work of raising a weight.
This idea seems to be missing from the article, and I would like to suggest that the article should include a rewritten version including the idea of potential (and not necessarily actual) conversion to the raising of a weight, as well as a more authoritative source if possible. Do others agree? Dirac66 ( talk) 01:07, 4 September 2015 (UTC)
Editor Dirac66 raises an important matter.
He is concerned, as I read it, about a distinction between work defined rather directly and simply, and work defined more indirectly and I would say more complicatedly. By direct and simple I mean that the system must deliver its work as a macroscopic force felt immediately by the surroundings. What happens further in the surroundings can be analyzed further when one has sorted out the concepts needed to describe the adventures of the system. A question may arise of whether the flow of electrons is a transfer of matter. I am inclined, at least for the present, to think that to escape being considered as a transfer of matter it should result in no net transfer of charge.
I am not sure where the proposal to define in terms of raising a weight comes from. I have read it in some texts that I find clever and self-confident but not too convincing. I think it is an attempt to create concreteness, but that it goes too far.
The questions arise in considering the adventures of the transferred energy in question as it occurs in the surroundings. I distinguish this from its adventures in the system. He emphasizes the phrase could have been.
Perhaps this is a way of talking about a distinction between work in the direct and simple sense, and what may be called 'generalized work'.
Editor Dirac66 writes "for example the electrical work of charging a battery can be completely converted into the work of raising a weight by an electric motor." This does not explicitly distinguish the system from the surroundings. It is not clear to me whether the battery or the motor is in the system or in the surroundings.
There may be a problem with defining things in terms of "the raising of a weight". It presupposes gravity acting on the weight. It may not be easy to arrange that the system be exempt from gravity while the surroundings have it. We have recently had some questions about whether the second law can be stated for systems in the presence of an external field. Part of the problem is the desire to jump in theory to continuously distributed inhomogeneous systems before homogeneous systems have been settled. I have carefully read the committee report, written by Alberty, cited by a certain redoubtable editor. I have further carefully read a major text by Alberty and others. My conclusion is that our redoubtable editor is not rightly reading Alberty.
I am not too sure about an authoritative source. There are very many more or less reliable sources. If there are significant differences among them then the question of Wikipedia point-of-view multiplicity may arise. Which, if any, is more authoritative? I think we ought to try to analyze and distill the best, at least as a first approach.
I think it most important that the more concrete and simple definition be given a good run, because of its fundamental place in the basic logic of the subject. Charging a battery is a chemical process and according to Prigogine and Defay, as I read them, is not in general reversible.
Another fundamental point that I think needs a good run is the distinction between the total energy of a system and its internal energy. The total energy is very often representable as the sum of three terms, the internal energy of the system, its kinetic energy as a whole, and its potential energy as a whole, obviously with respect to some externally imposed force field.
I think it important that the basic concepts be defined strictly in macroscopic terms, not relying on continuous field pictures of the system's internal content, expressed in internally spatial differential equations. The internal spatial differential equation approach should be derived from the macroscopic approach. The internal spatial differential equation approach is not good for an introduction in any case.
I suppose that further discussion may arise. Chjoaygame ( talk) 05:30, 4 September 2015 (UTC)
Having babbled airily about basic foundations, perhaps I ought to say more explicitly what I intend by that.
First we settle the system with respect to its surroundings, as to its velocity and attendant kinetic energy as a whole, and as to its position and potential energy as a whole. The remainder of its total energy is the internal energy.
Next, the internal energy is determined for a closed system, that is to say, for which matter transfer is not allowed by its walls. We further require processes that do not involve transfer of energy as heat. The system has adiabatic walls as its only dealing. All that is left are transfers as work. There is very strong opinion here that this is the foundational reasoning. This is why I think work should be treated very carefully.
Next we allow also transfer as heat, still forbidding transfer of matter. Thus we determine the mechanical equivalent of heat, and we use only mechanical units.
Next we allow also transfer of matter, through walls spatially and otherwise separate from those that allow the transfer as heat and work but not matter. We forbid heat and work transfers, and allowing transfer of matter we have only ΔU1 + ΔU2 = 0. Now it's time to be very careful indeed about our reference states, and we can find the amount of energy transferred in company with matter transfer, not uniquely resolvable into heat and work transfers.
As for the general setting. It doesn't matter in what order are the postulates are listed. It's all the postulates at once, or go back to the drawing board. One of the postulates in the established view is conservation of energy. The existence of adiabatic walls is also foundationally postulated in the established view. But the sequence in which the postulates are called upon in argumentative presentation does matter and is open to opinion while still not trying to alter the basic postulates. Chjoaygame ( talk) 08:13, 4 September 2015 (UTC)
Thank you for your response.
Denbigh and Kestin ring bells for me, but I need to go to the library to get them.
As a very loose and vague statement, open to immediate change or denial, perhaps one might say that what happens in the surroundings is less scrutinized than what happens in the system. Very loosely thinking, perhaps one might say that work done on the surroundings is allowed to be done on ideal work transducers, as a matter of convention? This would create problems for some statements of the second law, I think? I would think it a mistake to allow the battery as an ideal work transducer because it happens by chemical reactions, which are irreversible, because they change many disorganized single ions or molecules, not obviously macroscopic items.
Haase [1] has a section on work on pages 19–24. Amongst other things he says that P dV is not an exact differential, which I think may show that I was wrong to allow a recent edit that removed a caveat that required reversibility. Haase in that section cites only Guggenheim and Callen. He writes as follows on page 20.
No explicit mention of gravity there. Perhaps that is a weakness in his presentation? He explicitly restricts the section to refer only to closed systems.
More to think about here. Need some time. Chjoaygame ( talk) 01:48, 5 September 2015 (UTC)
Not much luck right now in library. Denbigh: two editions out on loan, one in Engineering Store, one in General Store. Kestin: in Engineering Store. All take days or weeks to get. Andrews and Saad not held. Chjoaygame ( talk) 04:36, 5 September 2015 (UTC)
An extract from the present article:
This may partly address our present concerns.
An extract from Callen:
So I was wrong to let that edit through. I will shortly fix it.
Münster has little to say about work immediately relevant to the weight-lifting thing. He writes:
in agreement with Callen. Chjoaygame ( talk) 09:03, 5 September 2015 (UTC)
On page 31, Silbey, Alberty, & Bawendi write "Work is often conveniently measured by the lifting or falling of masses." Chjoaygame ( talk) 23:16, 5 September 2015 (UTC)
Thank you for this reply. Looking in the article, I see quite a lot of text. Of that, I have contributed some, and perhaps some of that needs correction.
At the end of the article's text is the following:
The lead starts as follows:
Perhaps these points have more to do with the section above on this talk page, headed work or generalized 'work', and might be further discussed there. The present section is about using lifting a weight to put work in a nutshell, as you are proposing, and I am happy about. Chjoaygame ( talk) 05:45, 6 September 2015 (UTC)
The library responded quickly. Here follow some findings.
Denbigh 1st edition reprinted 1957
Page 14:
The wording of the last, just previous, sentence is slightly different in the 4th edition (1981/reprint 1993).
Kestin 1966
Chapter 4, pp. 110–148.
[Discussion of the difference between raising and lowering of a weight, in terms of what could be so.]
[Discussion of reversible, irreversible, and quasistatic processes.]
It seems to me that Kestin is here talking about 'work in reversible and quasistatic processes', not the same as the phrase I proposed, 'generalized work'. I think our present article is also talking about work in reversible and quasistatic processes.
This last remark is not reflected systematically in the present article. Chjoaygame ( talk) 00:11, 9 September 2015 (UTC)
Perhaps my following the references has sidetracked too much from Editor Dirac66's proposal to put in a section about potential to raise a weight. Perhaps I should repeat here that I am happy with his proposal. Chjoaygame ( talk) 08:32, 15 September 2015 (UTC)
I have undone a good faith edit. The edit is over-explanatory. If the work is done on the system, it is counted as work, even if it is frictional. Some of the frictional work may be done on the surroundings, and become internal energy of the surroundings, and then pass to the system as heat; that is energy passing to the system as heat, not as work done on the system. The system does not do work as friction on the surroundings. Chjoaygame ( talk) 23:39, 2 January 2016 (UTC)
Just a small discrepancy I noticed while having to correct two links contained in the Enthalpy wiki article to the section of this page: Work_(thermodynamics)#Pressure–volume_work. The issue was that they linked to Work_(thermodynamics)#Pressure-volume_work (with a hyphen, not an en dash) instead of Work_(thermodynamics)#Pressure–volume_work (with an en dash, not a hyphen). In this article ( Work_(thermodynamics)), there are 11 cases of "Pressure–volume work" with an en dash, and 2 cases of "Pressure-volume work" with a hyphen. I imagine that it is easy to make the mistake of not using an en dash when linking to Work_(thermodynamics)#Pressure–volume_work, like what happened in the Enthalpy article. Further, according to this article: https://www.grammarly.com/blog/en-dash/ , en dashes should only be used in complex compound adjectives, not regular compound adjectives. This article: https://www.dailywritingtips.com/en-dashes-clarify-compound-phrasal-adjectives/ seems to agree. And take a look at Bose–Einstein_condensate. It contains mostly en dashes, but some of the sources at the bottom also contain hyphens (use your browser's search function to search for – or -). https://english.stackexchange.com/questions/2116/when-should-i-use-an-em-dash-an-en-dash-and-a-hyphen seems to agree as well (feel free to check this source).
Now, in the case of "Pressure–volume work" or "Bose–Einstein condensate", the en dash is being used in place of an "and". According to wiki article Dash (as of March 30, 2019):
The French and Indian War (1754–1763) was fought in western Pennsylvania and along the present US–Canada border (Edwards, pp. 81–101).
Notice how it says [Not in citation given]. I wasn't able to access the source to check if the en dash can be used instead of "and".
Given the above, it seems as though that the hyphen should be used instead of the en dash. Unless there's better evidence to the contrary. -- 174.57.210.161 ( talk) 04:35, 30 March 2019 (UTC)
This dispute at talk:Heat puts under question whether this article is named correctly. TL;DR: the present article restricts itself to reversible work. How do thermodynamics textbooks describe Joule’s paddles (a.k.a. “isochoric work”)? Incnis Mrsi ( talk) 15:06, 28 July 2019 (UTC)
A tag has been posted, asking "according to whom?", about the sentence "When it is done isochorically, and no matter is transferred, such an energy transfer is regarded as a heat transfer into the system of interest."
The currently used definition of heat transfer is that it is transfer of energy to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter.
The energy transfer in this case is supplied by externally applied work, defined as work in the surroundings, that does not act through immediate direct effect on the state variables of the system that define thermodynamic work for the system, for example volume, but, rather, acts on the system through friction. The energy transfer is not by transfer of matter. Chjoaygame ( talk) 11:28, 29 July 2019 (UTC)
The definition of Heat in the respective wikipedia aricle has the answer. Any transfer of energy between 2 systems occur as heat. The Joule's paddle example is the same. If Incnis Mrsi understands the Joule's paddle process, he/she must have had understood the question's answer, and there would have been no need of this according to whom?. So, I would suugest him/her to go through it carefully. Lichinsol ( talk) 14:29, 29 July 2019 (UTC)
If nobody objects, then I replace “… regarded as a heat transfer into…” with “… regarded as transformation to heat input for…”. Incnis Mrsi ( talk) 14:58, 29 July 2019 (UTC)
Yes, as Chjoaygame says near the end of the above discussion, there is a difference on Wikipedia between Wikilinking and Citing a reliable source. Here, two plus years after the above discussion, no one has yet answered the question "According to whom" by providing a reliable source. Wikilinks help to explain words which may be unfamiliar to some readers, but Wikipedia policy is that non-obvious and especially controversial statements are supposed to be supported by reliable sources. Reading quickly, we seem to have several conflicting opinions in the above discussion. Can someone please provide a reliable external source for the claim in the intro that isochoric Joule heating without matter transfer is just heat transfer. One might argue that it is electrical work used to heat the system. Is there a textbook or review article that clearly says one or the other? Dirac66 ( talk) 00:18, 10 October 2021 (UTC)
I have undone this good faith edit.
The edit has the merit of brevity. But it is so brief that a newcomer would get inadequate guidance to its meaning. Chjoaygame ( talk) 00:17, 24 October 2020 (UTC)
Thermodynamic work can be distinguished from work done by agents or factors in the surroundings. For a closed system, the latter can be conceptually split into work that changes only the 'work-like' state variables of the system, for example P–V work, and what engineers call 'shaft work', used in Joule's paddle-wheel experiment, also called 'isochoric' work by some physicists. Such 'shaft work' or 'isochoric work' appears in the system's state variable increments as S–T energy. Chjoaygame ( talk) 02:20, 6 December 2020 (UTC)
"Mode of..." is useless overhead to something that is meant to be terse. How about "Reversible energy transfer between a system and its surroundings"? VQuakr ( talk) 21:21, 7 January 2021 (UTC)
Quoting: "No short description is a complete discussion of the topic."
Quoting: It is by its nature terse.
Quoting: Again, 2nd law doesn't preclude truly reversible processes, which do actually occur on a micro scale - "reversible" is fully accurate.
Quoting: 2nd law precludes the entropy of a closed system from decreasing, but does not prevent it from remaining constant.
Quoting: Where at WP:SHORTDES does it say we shouldn't use technical terms?
A short title is just a method of cataloging subjects, it does not have to, nor can it possibly, define terms with any kind of detail. This hackling is just more of the same shortsightedness that doesn't see the forest for the trees. kbrose ( talk) 14:39, 13 January 2021 (UTC)
I thank you for your interest. Nevertheless, I think 'distinguished' is the right word for the job. 'Distinct' doesn't have the same depth of meaning. The point is more than distinctness; it is special distinctness. An example of the difference is in group theory. The identity element (0 for additive groups) is more than just distinct. Every group element is distinct. But 0 is special, and it is customary to express this by saying that it is distinguished. I think this custom is suitable here. For example, isobaric processes constitute a distinct class of processes, but I think they are not distinguished in quite the same way as are work, heat, and matter transfer, which are distinguished in the notation for changes of internal energy.
I agree that 'measureable' is better.
I thought about 'these' and 'those', and preferred 'those'. Chjoaygame ( talk) 21:23, 13 April 2023 (UTC)
@ Dirac66: Hi, Dirac66. I would be glad of a reply to the above. Chjoaygame ( talk) 08:22, 15 April 2023 (UTC)