On Mon, 19 Jun 2006 12:01:37 -0700, Roy Lewallen
wrote:


do it. What the U.S. did was to declare the metric system to be official
("Mission Accomplished!") and change whiskey bottles from fifths to 750
ml (which was promoted by the booze industry because it made the bottles
just a little smaller and they could charge the same price). Wow.

Roy, you overlooked that the US, an earlier signup to SI, fixed the
spelling of metre in the US variant of SI.

Owen
--

Dear Howard W3CQH:
You have not been clear about what information you need. What do you
wish to accomplish?

Here is Section 207:

Telecommunications Act of 1996

SEC. 207. RESTRICTIONS ON OVER-THE-AIR RECEPTION DEVICES.
Within 180 days after the date of enactment of this Act, the
Commission shall, pursuant to section 303 of the Communications
Act
of 1934, promulgate regulations to prohibit restrictions that
impair a viewer's ability to receive video programming services
through devices designed for over-the-air reception of television
broadcast signals, multichannel multipoint distribution service,
or
direct broadcast satellite services.


It sure is not clear what this has to do with what you have said so far.

...... and, in "real" engineering: Kg is the unit of mass in the SI mks
system. Newton is the unit of force. F does equal MA (at least for low
velocities).

73 Mac, N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Howard W3CQH" wrote in message
...
Thanks to all that have answered my original post - but the information
that
I seek has not been answered.

I understand that section 207 of the FCC telecomm act 1996 contains
information that I might be able to use to help me in this matter. Where
can I obtain a copy of Section 207? I cannot find it posted on the FCC
website!

Thanks,



"Howard W3CQH" wrote in message
news
Looking for specs on any log periodic antenna that covers 50Mhz -
1300Mhz,
(Ham variety). Specs must also contain that it can withstand 80MPH wind
and 30 Lbs of ICE?

Thanks and best DXin.

de Howard W3CQH

gravity wrote:


please read the NIST publications which define the Avoirdupois pound in
terms of kilograms. this is not debateable since NIST is *the* authority in
the US.

The NIST isn't the authority on the laws of physics. One of the most
basic of which is F=MA, if you use pounds for mass in that formula you
get the wrong answer. Nothing that NIST says will change that.

200 lbs = 6.25 slugs * 32 ft/sec^2. Using pounds, the formula won't
work any other way.

--
Chris W
KE5GIX

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Chris W wrote:
Owen Duffy wrote:


I was taught (in imperial units) to differentiate mass (pound) and
force (pound-force). That learning stood me well when we changed to SI
(metric) part way through school.


You were taught wrong. If you use pounds in a formula that wants mass
such as F=M*A you will get the wrong answer. So lets say you weigh 200
lbs on earth where A = 32 ft/sec^2. You can then calculate your mass by
solving for M = F/A or 200/32 = 6.25.

If you "weigh" 200 lb (no s at the end of unit symbols) on Earth, that
_is_ your mass, in normal usage in either the medical sciences or in
sports, which are of course the purposes for which we normally weigh
ourselves.

You can, of course, use those 200 pounds in the F = ma formula. For
example, if you accelerate those 200 pounds at 40 ft/s², the force is
8000 lb·ft/s², which is, of course, 8000 poundals, since a poundal is
the force which will accelerate a mass of one pound at a rate of 1
ft/s².


When you are doing physical calculations it is very important to use the
correct units, other wise you calculations are meaningless. Suppose you
want to know what you will weigh on the moon where the acceleration due
to gravity is 5.25 ft/sec^2. F = M*A if you use 200 for your mass you
get, 200 * 5.25 = 1050, that indicates you would weigh 1050 lbs on the
moon. Which is clearly wrong. Trying again with the correct units and
you get, 6.25 * 5.25 = 32.8, now that sounds more like what you would
weight on the moon.

Not at all. It indicates that you exert a force due to gravity of 1050
poundals (not lbs) on the moon. On Earth, you would exert a force of
somewhere in the neighborhood of 6410 poundals to 6450 poundals,
depending on your specific location.

Not only is it just as easy to use an unfamiliar unit for force as it
is to use some strange unit for mass, but the absolute
foot-pound-second system (which includes poundals) has been around
considerably longer than the gravitational foot-pound-second system
(which includes slugs), and rather than either of those systems, those
still using English units are more likely to use the engineering system
which includes both pounds and pounds force, but neither slugs nor
poundals. Since that system is not a completely coherent system, of
course, many of the formulas need to be adjusted with a g_c factor, a
dimensionless number equal to the ratio of the acceleration used to
define a pound-force to that used to define a poundal, or g_c = (32.174
ft/s²)/(1 ft/s²) = 32.174

In the non scientific world, where the metric unit KG is used for
weight, M=F*A works just fine if you put what you call "weight" in KG in
for M in the formula.

The symbol for kilograms is kg, not KG. There is nothing different
about the weight in the English units world, where the pound used for
this purposes is, by definition, exactly 0.45359237 kg.

Gene Nygaard

Chris W wrote:
gravity wrote:


please read the NIST publications which define the Avoirdupois pound in
terms of kilograms. this is not debateable since NIST is *the* authority in
the US.

The NIST isn't the authority on the laws of physics. One of the most
basic of which is F=MA, if you use pounds for mass in that formula you
get the wrong answer. Nothing that NIST says will change that.

200 lbs = 6.25 slugs * 32 ft/sec^2. Using pounds, the formula won't
work any other way.

Bull****.

Here are a couple of other ways that work just fine with FFU:

200 lb * 32.2 ft/s² = 6440 pdl

0.52 slinch * 386 in/s² = 200 lbf

Be sure to distinguish pounds force (lbf) from pounds (lb), and units
of measure should remain unchanged in the plural, without adding any
language-specific "s" or whatever.

Gene Nygaard