RadioBanter - View Single Post - Supporting theory that Antennas "Match" to 377 Ohms (Free space)

September 29th 03, 04:53 PM

On 29 Sep 2003 15:08:27 GMT, (Tdonaly) wrote:

Gene wrote,

Some of you likely are or have been science teachers. Use the
resources you have at hand to find this elusive official definition of
the pound as a unit of force. Tell me exactly what the standard is,
who defined it, and when.

I'm not a science teacher, but it wasn't hard to find. Look in the _Handbook
of
Mathematical Functions_ under "Physical Constants and Conversion Factors," by
A.G. McNish of the National Bureau of Standards (this is an old book). There
it is,
clear as a drunkard's gin, 1 pound force = 4.44822 Newtons. Speaking of
Newtons,

How old? When was it published (before or after 1959, in particular).

I will bet that Richard Clark won't endorse your finding as being any
sort of "official definition." What do you say, Richard? Did he find
a hidden treasure?

McNish also gives a conversion factor for pounds to kilograms, doesn't
he? From what you have given us, he identified the "pounds force" as
such. What does he call the pounds which are converted to kilograms?
Just "pounds"? Or "pounds mass"? Or just "pounds avoirdupois" and
"pounds troy" without saying that they are pounds mass?

I'll also bet that McNish didn't call them "Newtons"--it is newtons,
not capitalized in English.

Now, let's assume that this were an official definition. Then what is
the "standard acceleration of gravity" in English units? A pound
force is equal to a pound mass times the standard acceleration of
gravity. We already know a pound is officially defined as 0.45359237
kg, so that standard acceleration of gravity will be 1 lbf divided by
1 lb.

1 lbf/1 lb =4.44822 N/0.45359237 kg = (4.44822 kg m/s²)/0.45359237 kg
= 4.44822/0.45359237 m/s² or about 9.80664643896 m/s²

(4.44822/0.45359237 m/s²)(1 ft/0.3048 m) =
4.44822/0.138254954376 ft/s² =
32.17403687... ft/s²

That is indeed awfully close to the standard acceleration of free fall
which is official for defining kilograms force. But it isn't the
same, if that is an official definition of a pound force.

Newton, is the catty a unit of weight, force, or mass, and where is the
official
definition of same? What! No official definition of a unit that has been in
use for
thousands of years?

There are lots of official definitions--but since I don't read
Chinese, I'm not about to venture a guess as to whether or not any of
them are found on the Internet.

They are units of mass, of course. Originally represented by
independently maintained standards, and varying somewhat in different
countries. Just as pounds were and just as kilograms still are. But
at various times and places, and for various purposes such as
international trade, catties were officially redefined in several
different ways: as exactly 1 1/3 lb avoirdupois, as exactly 600 g,
and as exactly 500 g are just a few of those official
redefinitions--there might also have been one in terms of troy units,
perhaps 20 oz troy = 1 2/3 lb troy, and perhaps other redefinitions in
terms of either Spanish or Portuguese libras.

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/