Talk:Units conversion by factor-label

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[edit] Doesn't seem encylopedic

This doesn't seem encyclopedic. Perhaps this should be moved to Wikibooks? ―BenFrantzDale 06:44, 12 February 2006 (UTC)

I don't understand why you feel this isn't encylopedic. The factor-label method of using dimensional analysis for conversion of units has been in use by chemists and engineers for decades. Do a Google search on the keywords and phrases "units conversion", "factor-label", "dimensional analysis" and you will get a great many hits including very many high school and university course sources. The Wikipedia already includes an article on the more formal and rigorous use of dimensional analysis but it doesn't include the technique of conversion of units ... which I believe merits an article of its own.

mbeychok 18:14, 12 February 2006 (UTC)

I say it isn't encyclopedic because it seems very how-to. I think I am also biased against the article as is for style reasons (see my comments below). —BenFrantzDale 23:14, 13 February 2006 (UTC)

Also, one of the bolded AKAs is dimensional analysis, a page which already exists. ―BenFrantzDale 12:15, 14 February 2006 (UTC)

[edit] This page may need cleanup??

User:crissov has posted a tag saying this page may need cleanup but he did not explain why he had done so. If he will please tell me what he believes to need editing, I will do my best to cooperate. As the original author, I did my best to Wikify this page. The subject matter is not included anywhere else in the Wikipedia and I made a very diligent search before providing this contribution.

I have removed the tag until Crissov and I have had more discussion ... I hope that is okay.
mbeychok 02:33, 13 February 2006 (UTC)

I agree with the need for cleanup. It could do with a proper lead section before any named sections and with the first sentence answering the question "What is units conversion by factor-label?". Also, the math would be better as TeX markup than as HTML. —BenFrantzDale 23:14, 13 February 2006 (UTC)

BenFrantzDale:

Thank you for clarifying your perception of this article. There are a good many articles in the Wikipedia which do not have a lead-in section. However, I will add a lead-in section as you suggested as soon as I can. As for using TeX equations, I have been unable to find any way of striking through (i.e., lining through) parts of a TeX equation ... and that is essential to illustrating the cancelling of conversion factors that is the very heart of the Factor-label method. Also, one of the three equations in the article would be too long in TeX to display it in the width of the display space without horizontal scrolling.

If you can tell me how to strike through parts of a TeX equation and also how to create a TeX equation in a smaller font, I will change the equations.

Thanks again for your response.

mbeychok 01:28, 14 February 2006 (UTC)

Crissov:

First, let me say that I really like your editing of this article. In particular, I like how you revised the first two equations and placed them in a box. In fact, I think what you have done with the equations will satisfy BenFrantzDale's desire to change the equations.

There are some minor changes that I made as follows:

• Although physicists and chemists understand that a mol is really a gram-mole and use it as such, most engineers (in particular chemical engineers) and many others make a distinction between a gram-mol (gmol) and a kilogram-mol (kgmol). Therefore, I changed the  molecular weight of NOx = 46  to the  molar mass of NOx = 46 kg/kgmol. That makes it consistent with the 22.414 Nm³/kgmol used in the flue gas example ... since there are only 22.414 L/gmol (or 22.414 L/mol] and a liter is 1/1000th of a cubic meter.

• Also, most engineers and most people working for environmental regulatory agencies involved with air pollutants such as the nitrogen oxides refer to them as NOx rather than NO_x so I reverted those back to the NOx form. Also, that form is consistent with the NOx form used in the example conversion.

Sorry to be so long-winded, but I have one more comment that I hope will not offend you. Rather than just making the revisions without any prior discussion, it would have been nicer to be gentle and civil with a newcomer like myself by at least having some discussion and/or explanation.

Regards and thanks again. mbeychok 03:00, 14 February 2006 (UTC)

[edit] Addition of Physics Wiki Book to See also section

I see no harm to having had the FHSST Physics Wiki book included in the See also section. However, I would point out that it has a much less comprehensive coverage of the subject than does this article. - mbeychok 04:01, 26 February 2006 (UTC)

I think the issue is what should be in Wikipedia vs what should be in Wikibooks. There seems to be consensus that only general information should be in Wikipedia and more specific info should be in Wikibooks. I personally think everything should be in Wikipedia. I faced this same criticism myself and had to reluctantly moved material from trajectory into Wikibooks. Samw 05:06, 27 February 2006 (UTC)

[edit] Reason for reverting edit by User:217.84.189.114

Where did User:217.84.189.114 find a "rule" that brackets cannot be used around dimensional units? Even if such a rule exists somewhere, the case in point in this article is not a mathematical equation per se. Instead, it is an example of how cancelling dimensional units can be used to determine if a mathematical equation is dimensionally consistent. Replacing the brackets with parenthesis (as was done by User:217.84.189.114) resulted in double sets of parentheses which looks very confusing. It is much clearer when brackets are used. The edit by User:217.84.189.114 is a too rigid and too inflexible application of such a rule (if any exists). That is why I reverted his/her edit. - mbeychok 00:11, 24 July 2006 (UTC)

the rule is to find somewhere around or in ISO 31, but I don't insist on that because I don't know the source exactly - is there any reason not to use curly brackets instead? -- 217.84.175.39 09:38, 28 July 2006 (UTC)

Please, 217.84.175.39, stop messing around in the several "dimension" related articles. The square brackets mean "dimesion of" and in the articles where we have used italics, it is because they have been so used in the last 50 yrs. If there are "new" rules, show them . --Jclerman 10:58, 28 July 2006 (UTC)

Jclerman - did you even notice what I edited? The other ones were mistakes, which I accepted - no reason to pull out the lobe (is this the right expression in english?) -- 217.84.175.39 20:29, 28 July 2006 (UTC)

217.84.175.39, What you did in your edit (which I reverted) was to change:

(Pa) (m³) = (mol) [ (Pa·m³) / (mol · K) ] (K)

to this:

(Pa) (m³) = (mol) ( (Pa·m³) / (mol · K) ) (K)

and that, as I said before, resulted in double sets of parentheses which are very confusing. The primary purpose of Wikipedia is to provide information in a clear, easily understood manner. As I also said before, even if there is such a rule in ISO, so what? We shouldn't get excessively rigid and obsessive about such minutiae. Now, you changed the subject of your previous edit and asked Is there any reason not to use curly brackets instead? Yes, curly brackets would work but I like the look of square brackets better ... and as the original aurthor of this article, I chose what I liked better. Please honor that choice of mine. Surely, there are much more meaningful things in Wikipedia that need editing without concentrating on such trivial matters. - mbeychok 16:22, 28 July 2006 (UTC)

yes - it's your choice and I never said I wouldn't accept that ... I didn't make such a big thing out of that - I still think it is missunderstandable - but I don't really care, I just wanted to help and didn't make it worse - then I asked a question. So what? -- 217.84.175.39 20:28, 28 July 2006 (UTC)

[edit] Limitations section

Someone experienced, please just check if this new section I added is valid. It should be valid. --Ajo Mama 02:34, 12 December 2006 (UTC)