Re: Changing Cycles 'till it Hertz

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

	Thanks for the very interesting comments.

> Your point of view makes all sense for me. I really wonder from where
> come the weird idea of naming what is just a count as "Hertz", while
> something more useful as "radians per second" has no special name.

	I have a book on "plant control systems" which tends to express
frequency in radians/HOUR!  Of course, radians per second can also refer
to angular velocity, for which there is no SI unit.  I doubt that
confusion ever occurs.

> The name is nice, however, and shorter than "cycles per second" ;-)

	The old usage here was just "cycles" with the "per second" implied.

	Weird indeed!  The usage (at least now) comes with the SI units, which
MANDATES that  all "derived" units be given the names of prominent
scientists of the past - Hertz, newton, joule, pascal, etc.  The Hertz
is the unit of frequency and is (1/s) expressed in "base units", in this
case s being the second.  To my way of thinking, many of these
"scientific" units are of inconvenient size compared to the ones we used
to use.  The Tesla (10,00 gauss) is the first one which comes to mind
it's too large. The Newton unit of force (m^2.kg/s^2) is too small. 

	A treatise on SI "units and prefixes" can be found at:

	http://www.bms.abdn,ac.uk/undergraduate/guidestosiunits.htm

(I hope I didn't make a typo there, transferring the address from the
screen of my PC.)  

> About metric x imperial units, here we don't care much about the
> existence of the two systems, but most common units are metrical.
> Some time ago some regulating agency tried to force the use of metric
> units everywhere, resulting in those ridiculous conversions that you
> mention. Doesn't work. I frequently buy metal rods and ball bearings
> at two stores, one in front of the other. The rods are all imperial,
> and the bearings all metrical... For precise work, I collect metal rods
> from discarded printers, that seem to be all metrical, or order
> "imported" imperial bearings...

	By "Imperial" do you mean what I call "english" (inches, pounds,
gallons, etc.)?  There are also Imperial units of different size.
(Imperial gallons used to be used in Canada for the sale of gasoline,
and one imperial gallon is more than the one we use here.) 
 
> To add something that can be more useful for members interested in
> history. Take a look at this site: http://gallica.bnf.fr
> There is a large collection of old books and periodicals available
> for download there, including some interesting classic texts on
> electricity, most in French, but some in English and German too.

	Thanks for the reference.  Looks like a lot of interesting reading if I
can just invoke enough of my High School French to navigate it.  (We
tend to be less multi-lingual in this country than is common in other
more cosmopolitan countries.) 

> Antonio Carlos M. de Queiroz

Ed