Talk:Work (thermodynamics)

message: 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)
replies: text: I expanded on the path dependancy; I hope it makes sense. I thought that a slightly more physical explanation should precede the mathematical explanation, since many readers may be students less familiar with the math (just a guess). I don't think I addressed the above issues, however. I lack a good reference to use for a citation; hopefully someone else can read it, adjust/correct if needed, and provide a good reference, as I think this discussion is important to really understand the topic. Dhollm (talk) 08:25, 24 August 2010 (UTC)
thread_title:  sec pressure-volume work 

message: 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)
replies: text: Fixed. Better late than never. Dirac66 (talk) 21:08, 14 April 2013 (UTC)
thread_title: SI Units

message: The section on Mechanical forms of work would fit better in Work_(physics) Nobody Ent 12:28, 11 July 2012 (UTC)
thread_title:  Mechanical forms of work 

message: 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, , 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, , 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)
thread_title:  work and heat and transfer of internal energy 

message: 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)
replies: text: Mentioned contributions do not appear to comply with WP:SOURCE. I'd encourage you to re-read that. It needs to be immediately apparant where this information is from and why it should be trusted; linked contributions lacked that.--Melmann(talk) 12:17, 3 September 2015 (UTC)
replies: text: Following your admonition, I read "All material in Wikipedia mainspace, including everything in articles, lists and captions, must be verifiable. All quotations, and any material whose verifiability has been challenged or is likely to be challenged, must include an inline citation that directly supports the material. Any material that needs a source but does not have one may be removed. Please remove contentious material about living people that is unsourced or poorly sourced immediately."Chjoaygame (talk) 13:01, 3 September 2015 (UTC)

text: Though I would rather have seen Editor Hnedkovl or Supervisor Melmann do it, I have supplied references, in order to remove grounds for further chatter.Chjoaygame (talk) 18:05, 3 September 2015 (UTC)

text: I have followed this up, and made further edits. Indeed the edits were faulty and needed correction and references. For the formulas used, reversibility IS a requirement; my mistake. I have given the reason for this requirement.Chjoaygame (talk) 23:36, 5 September 2015 (UTC)
thread_title:  over-zealous undo 

message: 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:
:::::Examples of non-mechanical work modes include
:::::* Electrical work – where the force is defined by the surroundings' voltage (the electrical potential) and the generalized displacement is change of spatial distribution of electrical charge
:::::* Magnetic work – where the force is defined by the surroundings' magnetic field strength and the generalized displacement is change of total magnetic dipole moment
:::::* Electrical polarization work – where the force is defined by the surroundings' electric field strength and the generalized displacement is change of the polarization of the medium (the sum of the electric dipole moments of the molecules)
:::::* Gravitational work – where the force is defined by the surroundings' gravitational field and the generalized displacement is change of the spatial distribution of the matter within the system.
The lead starts as follows:
:::::In thermodynamics, work performed by a system is the energy transferred by the system to another that is accounted for by changes in the external generalized mechanical constraints on the system. As such, thermodynamic work is a generalization of the concept of mechanical work in physics.
:::::The external generalized mechanical constraints may be chemical,Guggenheim, E.A. (1985). Thermodynamics. An Advanced Treatment for Chemists and Physicists, seventh edition, North Holland, Amsterdam, . electromagnetic,Jackson, J.D. (1975). Classical Electrodynamics, second edition, John Wiley and Sons, New York, .Konopinski, E.J. (1981). Electromagnetic Fields and Relativistic Particles, McGraw-Hill, New York, . (including radiativeEssex, C., Kennedy, D.C., Bludman, S.A. (2005). "The nonequilibrium thermodynamics of radiation interaction", Chapter 12, pages 603-626 in Variational and Extremum Principles in Macroscopic Systems, ed. S. Sieniutycz, H. Farkas, Elsevier, Amsterdam, .), gravitationalNorth, G.R., Erukhimova, T.L. (2009). Atmospheric Thermodynamics. Elementary Physics and Chemistry, Cambridge University Press, Cambridge (UK), . or pressure/volume or other simply mechanical constraints,Kittel, C. Kroemer, H. (1980). Thermal Physics, second edition, W.H. Freeman, San Francisco, . including momental, as in radiative transfer. Thermodynamic work is defined to be measurable solely from knowledge of such external macroscopic constraint variables. These macroscopic variables always occur in conjugate pairs, for example pressure and volume, magnetic flux density and magnetization, mole fraction and chemical potential. In the SI system of measurement, work is measured in joules (symbol: J). The rate at which work is performed is power.
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)
thread_title: response 3

message: The library responded quickly. Here follow some findings.
Denbigh 1st edition reprinted 1957
Page 14:
:::::1.5    Work
:::::   The notion of work is not regarded as being in need of definition in thermodynamics, since it is a concept which is already defined by the primary science of mechanics.
:::::...
:::::   It may be noted that all forms of work are interchangeable by the use of simple mechanical devices such as frictionless pulleys, electric motors, etc. The correct usage of the term 'work' implies that the particular type of work which is under discussion may always be expressed in terms of the raising of a weight.
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.
:::::   The concept of work in thermodynamics is a natural extension of the concept of work in mechanics. This extension is required to take into account the greater variety of phenomena encountered in thermodynamics. ...
:::::...
:::::4.4   The definition of work in thermodynamics
:::::   In generalizing the preceding concept of work to include phenomena other than those encountered in mechanics, an attempt must be made to divorce it from the need to consider forces, and yet to preserve its essential physical characteristics. We can recognize the latter by rephrasing the definitions of the preceding section in thermodynamical terms. ...
:::::...
[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.]
:::::[p. 130]... It is clear that all natural processes are irreversible and that reversible processes constitute convenient idealizations only.
:::::4.8   General form of expressions for work in other reversible and quasistatic processes
:::::   In order to establish expressions for reversible and quasistatic irreversible work for systems other than the one considered in Section 4.5, it is first necessary to study empirically their general characteristics, and to establish their equations of state ...
:::::...It can, however, be stated at the outset that the reversible work can be represented by a single product of the form
::::::::::::::                                                (4.26)
:::::in the case of a system with two independent variables.
:::::...
:::::This similarity induces us to call all intensive properties  which appear in the expression for elementary work by the common designation of generalized forces, whereas all extensive properties  are known as generalized displacements. ...
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.
:::::[p. 144]   The work performed by a system during a reversible process can be computed by observing the system itself, because all quantities in the expression for work can be expressed in terms of its state. In the general case, this is impossible and the interaction between the system and its surroundings must be known in detail.
This last remark is not reflected systematically in the present article.Chjoaygame (talk) 00:11, 9 September 2015 (UTC)
replies: text: OK, I have now made a start and inserted a brief final section with what I consider the essential point, based on what I suggested  at the end of Response 1 above. I have not gone into all the points in the above discussion, so editor Chjoaygame or others may wish to expand the section.Dirac66 (talk) 21:02, 2 October 2015 (UTC)
thread_title: luck in the library

message: 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)
thread_title:  If it is received as heat, it is heat 

message: 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)
replies: text: An isochoric process is generally not reversible; it is not an example of thermodynamic work. VQuakr (talk) 15:19, 28 July 2019 (UTC)
replies: text:  Really it’s reversibility of Joule’s work-to-heat converters which is discussed here? Again: such gurus as Planck, Born, or H.B. Callen certainly addressed Joule-style processes. They had to develop some terminology to distinguish them from work determinable with state variables. Incnis Mrsi (talk) 15:43, 28 July 2019 (UTC)

text: Th Joule's paddle is an example of mechanical work being converted to heat. It is irreversible. This gravitational work cannot be regarded as a thermodynamic work. It is called isochoric as it does not change the volume of water, and thus no thermodynamic work is done, only the internal energy of water changes.Lichinsol (talk) 15:41, 28 July 2019 (UTC)

text: The Joule-style processes -- which  is referring, as probably the processes in which energy conversions take place(like mechanical energy to heat, or electrical energy to heat)-- can be distinguishly calculated by proper experimentations. Factors such as gravity, tension,etc are the working variables in Joule's paddles, and the usual thermodynamic processes have their state variables.Lichinsol (talk) 16:06, 28 July 2019 (UTC)
thread_title:  Confusing title 

message: 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)
thread_title:  Reason for undo of good faith edit