# Talk:Defining equation (physics)

WikiProject Physics (Rated C-class, High-importance)
This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C  This article has been rated as C-Class on the project's quality scale.
High  This article has been rated as High-importance on the project's importance scale.
WikiProject Measurement (Rated C-class, Top-importance)
This article is within the scope of WikiProject Measurement, a collaborative effort to improve the coverage of Measurement on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C  This article has been rated as C-Class on the project's quality scale.
Top  This article has been rated as Top-importance on the project's importance scale.
WikiProject Articles for creation (Rated C-class)
This article was created via the article wizard and reviewed by member(s) of WikiProject Articles for creation. The project works to allow unregistered users to contribute quality articles and media files to the encyclopedia and track their progress as they are developed. To participate, please visit the project page for more information.
C  This article has been rated as C-Class on the project's quality scale.
 This article was accepted on 20 June 2011 by reviewer Noleander (talk · contribs).

## Deletion requested

I was intending to move Wikipedia talk:Articles for creation/Defining equation (physics) to article space (I consider the draft article acceptable) and accidentally copied/pasted the text. So the edit history & original editor were lost. I'm asking for an admin to delete Defining equation (physics) so I can do the move properly. Thanks. --Noleander (talk) 23:32, 20 June 2011 (UTC)

It was done. --Noleander (talk) 21:40, 6 July 2011 (UTC)

## Relativity?

Maschen: are you sure the items in the "Relativity" section belong in the article? They dont look like they are "quantities". I think the article should be limited to quantities that have a unique, commonly used unit of measurement. The 2 items in Relativity section are starting to verge on equations that are not "quantities". --Noleander (talk) 21:40, 6 July 2011 (UTC)

## Relativity is no more

Good point actually. As you said the matrix isn't really a defined quantity, just useful for 4-vector Lorentz transformations. The Lorentz factor is to some extent a definition, but only for conveineince. I don't really see the problem with dimensionless quantities, except that it seems to contradict my own explaination at the begninning of this article...

To reduce the size of the article List of elementary physics formulae, many of the equations were moved to here, I didn't know where else to put these 2 items...

Lets just delete them. They were here to emphasize their common occurance but are so well-known on other relativity articles that they may as well be deleted from this article.

Thanks for feedback, Maschen (talk) 21:34, 17 July 2011 (UTC)

## Wave vector formulation

Before anyone asks, I am aware of the apparent complexity of the vectorized wave kinematic equations, but its only appearance. For waves, the two directions of motion to consider are parallel to some direction, and perpendicular to it. Using the unit vectors $\mathbf{\hat{e}}_{\parallel} \,\!$ and $\mathbf{\hat{e}}_{\bot} \,\!$ allows a more direct physical interpretion as to which directions are considered. At the same time familiar notation for common scalar formulation is present. Maschen (talk) 13:48, 19 August 2011 (UTC)

## Intro extended

I re-wrote the introduction to include facts about defining equations. More links and referances will be added soon. I'll probably delete the physical chem section to reduce the size of the article at some point. My eyeballs are glazed right now so please be patient for any mistakes...

Maschen (talk) 00:02, 6 September 2011 (UTC)

## Physical chem is no more

I moved all the physical chem stuff to a new article: Defining equation (physical chemistry). Hope it relieves the size of the article. Maschen (talk) 18:22, 9 September 2011 (UTC)

## Dimensions of amount of substance

Humilaiting for me to only notice now, but the amount of substance has the unit mole and dimension symbol [N]. The amount of substance is not a dimensionless quantity, it is related to the number of elementary units but not a pure number. I have reverted the change [N] -> dimensionless, back to [N], a dimension is different from a unit. See section Other fields of physics and chemistry in Dimensional analysis#Great Principle of Similitude, also the resources in the sources section for this article state that the amount of substance has a dimension, in particular Essential principles of physics by Whelan & Hodgeson, 1978, John Murray (publisher) says so. Maschen (talk) 14:40, 16 September 2011 (UTC)

## insert thermodynamics back

See here, thanks. 06:56, 9 May 2012 (UTC)

## Removal of content

I am currently in the process of rewriting constitutive relations and will be removing constitutive definitions from this article to that one (see the link at the top of the article). Removed content may be stored in my sandbox User:F=q(E+v^B)/sandbox. Please do not add constitutive stuff back in - some editors/IP's seem to have done this, yet article is long enough and it makes sense to share the load with a parallel yet underdeveloped article... 20:34, 22 May 2012 (UTC)

## The new plan for these types of articles

Since there are other articles (linked to here by merge banners) that include a list of physical quantities in table format with SI names, equations, units, dimensions, and comments/descriptions, which have a good format but are redundant with the scope of this article, I plan the following action:

No-one will of course read here... as you cna tell from the above threads, so will post on wikiprojects WP:measurement and WP:physics... assuming any response at all - if the consensus is a clear yes then it'll happen, else redundancy and repetition will remain in this little selection of articles... See also here. Maschen (talk) 12:57, 11 September 2012 (UTC)

This has been declined by others (including me) and will be split out to separate articles soon (i.e. reverse of merging). Maschen (talk) 07:50, 13 September 2012 (UTC)

Content has been moved out everywhere and this article will now be rewritten to discuss the nature of defining equations. Maschen (talk) 00:52, 15 September 2012 (UTC)