[amsat-bb] Re: AMSAT-NA totally metric?
kc6uqh at cox.net
Sat Jan 20 23:20:27 PST 2007
What is the equivelent of Board Feet of Lumber? Threads per inch or mm OK,
but why this pitch stuff?
Anyone got metric back gears for my WW II South Bend lathe ? Don't suggest
some made in China junk with a AC motor. Think the US Goverment is going to
give me a new one to be metric? Dream on!
A minute is a Nautical Mile (6000) feet in latitude. ( 100 feet per second)
Latitude times the COS of the latitude for longitude. (At 33N = 1 second of
longitude = 84 feet) Try that in kilometers! Guess your GPS will do those
things for you. FYI: A grid square is only square at 60 degrees of latitude.
COS = 0.5
On the other hand many caculations are simplified with metrics, wavelength
for example. Amps, Volts, Farrads, Henerys, Ohms, Frequency, and Watts are
same in metric and need no conversion.Grams, Litres and Meters require
developing a feel. I can visualize an inch, not 3 cm ? I can feel an ounce,
but not a gram, besides a pint is a pound of water! Is a litre of water a
Logic is often only in the eyes of the beholder! Easy is only in the the
skill and knowledge of the craftsman!
----- Original Message -----
From: "Tony Langdon" <vk3jed at gmail.com>
To: <amsat-bb at amsat.org>
Sent: Saturday, January 20, 2007 6:16 PM
Subject: [amsat-bb] Re: AMSAT-NA totally metric?
> At 06:48 AM 1/21/2007, you wrote:
>>Here is an excerpt on the Canadian metric conversion experience.
>>Still today we
>>tend to convert to the old english system (old generation) but the new
>>generation are fully imbedded in the SI system.
> Conversion was pretty painless in Australia. I recall the latter
> years of dual measurements, just before we went metric
> only. Nowadays, everyone uses metric for weather related parameters,
> temperature, wind speed, pressure. For everyday use, most people use
> metric or a mix of metric and the older units in everyday
> conversation. I am well versed in both systems, because of the time
> I grew up with and a natural aptitude for dealing with different
> measurements, and these days, I can do a lot of common conversions in
> real time in my head (as reasonably close approximations).
>>The harder part is the temperature system and the volume measures. A big
>>it is a decimal based system no more 1/64 1/32 and so on odd fraction. As
>>Asterix a small village still resist the conversion...
> Temperature seemed to be easier here, one rarely hears anyone use
> Farenheit here. Volume has some lingering artefacts (e.g. people
> still speak of "44 gallon drums", not "205 litre drums").
>>I remember the advertisement campaign at that time "don't convert
>>easier to say than doing.
> I can still think in terms of either system directly, without having
> to convert. :)
> In any case, when it comes to mathematical purposes, SI units are
> much easier to deal with - less oddball constants that have to be
> thrown into equations. I'm glad my university days were long after
> conversion to SI here. :-) And the speed of light happens to be a
> much nicer constant to work with (for calculating propagation delays
> and wavelengths). 300,000,000 m/s is much easier than 186,000
> miles/sec for quick mental calculations! ;)
> 73 de VK3JED
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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