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Old May 2nd 04, 10:23 PM
Herb Schaltegger
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In article ,
"Heinrich Zinndorf-Linker (zili@home)" wrote:

No, the problem with MANY (if not most) non-metric units is, that
there are often several localized versions of them - If you say (for
example) mile, pound or gallon, you can _never_ be absolutely, 100%
sure, which particular type of mile, pound or gallon is actually meant
- especially for people that are grown up in regions, where the
reflective use of these units has not been teached. Strict use of
metric (SI) units avoids ESPECIALLY THAT problem.


No, yourself. In the context of sci.space.history and the history of
Project Apollo, the units questioned by the earlier poster "gallons,
feets and psi's" are all easily understood - as is the poster's
snobbishness and disdain for learning anything other than the system he
is most comfortable with. There are no "localized versions" at issue
with any of them vis a vis Apollo. The only definitions for these units
anyone need concern him- or herself with in this discussion are the
American ones.

For any other SI-snobs out there too lazy to look things up yourselves,
here are some basic conversions to keep you happy:

1 U.S. gallon = 3.79 liters
1 foot = 12 inches = 0.305 meters
1 inch = 2.54 centimeters
1 psi (pound per square inch) = 6.89 kilopascals
1 lbf (pound force) = 4.45 newtons

And there is the second problem of many redundant units - there is
absolutely no real need for a hundred or more different units for
mass, force, temperature, length (area/volume) and so on, for each of
are needed conversion factors that are _not_ simply powers of ten. In
SI there are only a very small couple of them.


Hate to break it to you, but when you start getting down to the nitty
gritty of the physics, the fundamental constants of nature don't give a
rat's ass about powers of ten. Doing the math itself in most
engineering applications is a hell of a lot harder than looking up a
silly conversion factor to change units at the end.

--
Herb Schaltegger, B.S., J.D.
Reformed Aerospace Engineer
Columbia Loss FAQ:
http://www.io.com/~o_m/columbia_loss_faq_x.html