Re: [Phys-L] dimensional analysis

[Larry Smith <larry.smith@snow.edu>]

On Jul 25, 2012, at 10:54 PM, John Denker wrote:

> On 07/25/2012 03:37 PM, Larry Smith wrote:
> > Seems to me that the term "dimensional analysis" is used in two
> > different ways.  Some sources use it to mean simply converting from
> > one kind of units to another (how many square centimeters are there
> > in an acre?); this usage of the term is also called the factor label
> > method.  Others use it to mean comparing the dimensions of the
> > physical quantities to find relationships between the quantities.
> >
> > Do the two uses fall along disciplinary lines (chemistry vs.
> > physics)?  Looking at many hits from a web search led me to that
> > tentative conclusion.
> >
> > What do you mean when you say "dimensional analysis"?
>
> ==============
>
> As for the chemistry versus physics angle, my advice is don't go there.
> I don't think there is any such angle, and even if there were, there
> would be no advantage to pursuing it.  My advice is to teach good science 
> based on good scientific explanations.  In this case, as in most cases, 
> no sociological explanations are needed.
>
> ========


I'm not really trying to go anywhere with this except to understand why so many people use the term as a synonym for "unit conversion." If you do a web search for "dimensional analysis"  you will find lots of pages and YouTube videos where they will teach you unit conversion; most of them seem to be by HS Chemistry teachers or the URL is a college chemistry department.  The explanations I was _expecting_ to find seem to be from physicists.  Linguistically the term "dimensional analysis" seems to fit what the physicists on this list have said much better than "unit conversion."  While sociological explanations may not be needed to understand the scaling concept, curiosity is part of my nature.  I wonder why people use the words they do.

Cheers,
Larry