# Talk:Mechanical–electrical analogies

This review is transcluded from Talk:Mechanical-electrical analogies/GA1. The edit link for this section can be used to add comments to the review.
Reviewer: Chiswick Chap (talk · contribs) 17:38, 15 March 2015 (UTC)

It's more than time that someone bravely agreed to review this fine but somewhat forbidding article. Fortunately it's so clearly and elegantly written that even my creaky old school physics had no trouble reading it through with the feeling that I was understanding it all. So here goes. Chiswick Chap (talk) 17:38, 15 March 2015 (UTC)

I would love to see a theoretical physics discussion of the origin of the analogy. On the surface, you could say we find it easy to think in terms of linear systems, so we think of components that act linearly. This leads directly to the same simple differential equations for different systems, especially when conservation of energy is a natural focal point for optimizing engineering applications.  The most natural of the possible analogies is the impedance analogy which the one most commonly used and first cited in this article. The reason for this is that charge in electrical components is simply replaced with meters in the mechanical components. There are no other changes. Capacitors allow charge to build up for a fixed dielectric distance and the analogous spring allows meters to build up for a fixed number of charges (which are the source of resisting compression). For small compressions and non-saturating amounts of charge, both are linear.  The same direct relation exists for inductors and mass: inductance (magnetism) from a classical view (pre-quantum) is a relativistic effect of charge build up per unit length, not a thing unto itself.  See Schwartz, Feynman, and Wikipedia. For small changes, it is again linear so V=L*di/dt instead of having to resort to full-blown relativistic equations. So it seems mass could be viewed from a pre-quantum perspective as the relativistic effect of (quark?) charges being brought closer together as a result of length contraction.  Again, it's linear for small changes in velocity so F=ma instead of using full-blown relativistic calculations. In short, linear electrical components control charge/length where length is held constant by the component, and mechanical systems do the same but hold the charge constant and allow lengths to change. This is simple enough that there should be some references out there that delve into the source of the analogies and thereby allow it to be included in the article. Ywaz (talk) 14:15, 5 November 2015 (UTC)

Articles titles tend to use singular, and litterature seems to document an analogy, e.g. A new analogy between mechanical and electrical system elements. The article body uses both forms. Should we use singular or plural form?
I've renamed the article to use singular, but now I see it has passed GA review, so I'd like to get some opinions. (Context: I was actually busy in Wikidata to help someone to classify a Mason circuit as analogy). --Dereckson (talk) 10:27, 9 October 2019 (UTC)

I really think you should have opened this discussion first.  I further think you should revert all that change.  The article discusses a class of analogies and how they are related.  It makes more sense to have a plural title.  We make the dog article singular because all breeds of dog belong to the same species.  The concept "dog" is one thing with all breeds being subsets and all individual dogs being elements of the same set.  In the case of these analogies, the impedance analogy and the mobility analogy are not part of some greater theory we can call "mechanical-electrical analogy".  On the contrary, they are separate and incompatible.  It is done either one way or the other.  Likewise the resistance–reluctance analogy is not compatible with the capacitance–permeance analogy.  They are two entirely different ways of doing things.  Your example (the Firestone paper) is referring to one particular analogy so of course it is singular.  How is that relevant?  Firestone repeatedly uses the plural in the paper when referring to analogies as a group.
By the way, what is this Mason circuit you mentioned?  A circuit is not an analogy. SpinningSpark 11:17, 9 October 2019 (UTC)
@Dereckson: SpinningSpark 13:35, 10 October 2019 (UTC)
I've moved it back.  Posted here, pinged, and e-mailed.  No response in three days, not even to say you ate thinking about it and will reply later. SpinningSpark 14:51, 12 October 2019 (UTC)

Please can someone add to the Hamiltonians:
1/. The nomenclature
2/. An explanation - what the heck is being desdribed?  — Preceding unsigned comment added by 2A00:23C4:1594:E600:49CE:1AC0:F728:8444 (talk) 14:58, 5 November 2020 (UTC) 

The article currently states that,
The Hamiltonian variables, also called the energy variables, are those variables r = (q, p), which are conjugate according to Hamilton's equations.
What is lacking in that needs explaining?
As I originally wrote the article (and the state in which it passed GA), it did not contain Hamilton's equations at all.  It had a much simpler statement, something along the lines that the Hamiltonian variables were those variables whose time derivative was the power conjugate variables.  There is really no need to have Hamilton's equation in the article at all in my opinion.  It does not really figure in constructing an analogy.  I suggest reverting to the original format, but perhaps with an additional statement that the name derives from the variables' connection with Hamiltonian mechanics.  The link to that article should be enough for anyone interested in that aspect. SpinningSpark 12:06, 23 November 2020 (UTC)
"The Hamiltonian variables, also called the energy variables, are those variables r = (q, p), which are conjugate according to Hamilton's equations.
What is lacking in that needs explaining?"
What r, q and p ARE would be a start !!!
I know this is probably a 'stupid' question, but this is Wikipedia, not a PhD level maths textbook.
For every equation, please give the nomenclature and examples with physical units. 51.219.114.246 (talk) 11:54, 10 July 2023 (UTC)

I suggest adding a section on physical implementations of a mechanical-electrical analogy. I am aware of one mechanical system that provides a close analog to a wide range of electrical circuits: the toy Spintronics. As mentioned in the article, one of the main purposes of the mechanical-electrical analogy is to make an abstract topic more tangible, but it is not currently used this way in the article itself. Some pictures and a description of a real-life mechanical analogy could greatly benefit readers, hopefully making this fairly abstract article more tangible.
I have a big conflict of interest, so I hesitate to edit the article myself, but I'll provide as much material as I can for another editor interested in including it in this article. I'll be happy to answer questions. I'd also be happy to give a first pass at writing it. I'm not sure what the custom is for this sort of thing. Thanks!


### Useful pictures:
### Useful references:
The Spintronics website and the Science of Spintronics page
A simulator of Spintronics
US application 2021343184A1, Paul Garrett Boswell, "Mechanical Analog of Electronics", published 2021-11-04 
Pgboswell (talk) 18:58, 4 August 2023 (UTC)