RV-7a baggage area

"James R. Freeman" wrote in message ...
He is right. Gravity is not constant from one location to the next. For
example if we look a W. 105 and move to W. 15 we have moved from a gravity
hole to a gravity peak.The core of the Earth is like spinning a egg, in our
case the core has not come up to the speed of the surface and locations of
higher mass move but give us the 2 valley 2 peak problem in mass/gravity. It
is very much to note if You are doing station keeping on a geo-syn sat. .

You can also stay at the same location and exoperience varions
in the _apparent acceleration_ do teo gravity. I wouldn't call that
Gravity not being constant. For Gravity to be inconstant would
require that the Gravitational constant vary.

--

FF

On 12 Dec 2003 09:05:15 -0800, (Fred the Red
Shirt) wrote:

Gene Nygaard wrote in message . ..
On 11 Dec 2003 09:52:27 -0800, (Fred the Red
Shirt) wrote:

Gene Nygaard wrote in message . ..
On 10 Dec 2003 06:50:50 -0800, (Fred the Red
Shirt) wrote:



I was merely pointing out that you have it ass-backwards. There is
absolutely no looseness in the use of pounds as units of mass.

Non-sequitor. Loosness was never at issue. At issue was ambiguity.
Pounds can be either a unit of mass or a unit of force and often that
is not even made clear by the context. That pretty well fits the
defintion of ambiguous, does it not?

Slugs, OTOH, are only defined as units of mass. No ambiguity there.

The OP referred to slugs as ambiguous. The OP had it bass akwards.

--

FF



It is pounds force that are the recent spinoff, not the other way
around. It is pounds mass that are the venerable units, and pounds
force which are the *******ization, not the other way around.

I missed this part last time--I saw your signature above in the bottom
of the window, and assumed that the above was all you had written, and
didn't scroll down to see the rest and didn't see it when I replied
either.


Was not the pound ever defined as a unit of weight?

Certainly. But that doesn't mean "not mass."

See below regaring how weight is defined differently in differnt
theories.


Look at the millions of items in the grocery stores and in the
pantries of our homes today that list the "net weight" of our foods
and various other hardware and automotive products. The pounds on
them are every bit as much units of mass as the grams which appear
right alongside them.

I certainly hope that when they quantify the good they mean pounds
mass and not pounds force.


Like I pointed out to Russell a long time ago in this thread, the troy
system of weights also includes pounds and ounces. But unlike their
avoirdupois cousins, and unlike grams and kilograms, the troy units of
weight are always units of mass. They have never spawned units of
force of the same name.

What you address here is an vagueness in human language, not an
ambiguity in natural law.

Good grief. What in the world do you think we've been talking about.
Of course, it is linguistics.


What's really strange is that there are always some fools who will
insist that when we buy and sell goods by weight, we'd want to measure
some quantity that varies with location. How stupid can some people
be?

I never found any who wanted to do that, nor anyone who does
because on a practical level wherever the measurement is made,
even if it is made by actually measuring force, the variance
is so small that most normal folks consider in negligible, or
rather it IS so negligible that no one has any reason to consider
it at all. I'll be damned if I can understand why you find that
miniscule variance to be so disconcerting.

It is a whopping 0.53%, even if you limit yourself to SEA LEVEL.

Throw in Mt. Chimborazo, the highest mountain on Earth, and it gets
close to 3/4 of a percent; more than 1 part in 140.

Now, if you have a standard 400 oz t bar of platinum, do you suppose
it would make a difference if they were units of force rather than
units of mass? Would three ounces at $600/oz matter?

Buyers of gold and other precious metals were more particular than
that even 2000 years ago.



Get it through your thick skull that "weight" is an ambiguous word,

I understood that already and am quite prepared to explain it.

In Newtonian Physics, 'weight' is a force. Mass OTOH is the factor of
proportionality between force and acceleration.

In General Relativity, 'weight' is a geometrial distortion of
space-time due to the presence of mass.

So weight is either a force or a geometrical effect, depending on
which model you happen to be using at the time.

Those models only explain weight AFTER you have chosen to define it as
the effect of gravity.

In common parlance, 'weight' is either or both, or even mass,
or most often, none of the the above because in common parlance,
one generally does not assume any specific physical theory and
it is quite common for people to use words without regard to any
formal definiton at all.

one with several different meanings. Note also that "net weight" is
not a physics term. If you are talking about a "weight" which is the
force due to gravity, then you can't ignore the container, unless
you've invented something that is invisible to gravity. Whenever
anybody talks about "net weight," that weight is the very same thing
as what physicists often call "mass" in their jargon.

Are you unfamiliar with the concept of the superposition of forces?


If it was
defined as a unit of weight then it was simultaneously defined as
a unit of force without regard to whether or not the person(s)
defining it UNDERSTOOD that they were doing so.

Bull****.

The meaning of "weight" which is a synonym for "mass" in physics
jargon

Can you state the formal name any internally consistant physical
theory in which weight and mass are synonyms? As illustrated above,
that is true of neither Newtonian Physics, nor General Relativity.

There are different quantities involved here. But there is no
"natural law" which tells you what word you should be using for any of
them.

You can choose to call a certain quantity "weight." Your doing so,
however, does not magically erase other meanings which the word
already had.

I know of no physical theory, nor any physicist that uses the words
weight and mass interchangeably within the discipline of physics
itself.

In the first place, what in the world gave you the idea that what
physicists do has anything whatsoever to do with "baggage weight"?

In the second place, it isn't true. Ever heard of atomic weight?
Molecular weight? If not, go look at some of the hundreds of
different periodical tables available on the internet, many from
colleges and universities around the world.

Do you remember the days when atomic weight in physics was different
from atomic weight in chemistry? When one of them defined it based on
oxygen-16 being 16.0000, and the other defined it based on the natural
mix of oxygen isotopes being 16.00000?

is quite proper and legitimate, well justified in history and
in linguistics and in the law.

Have you never heard the adhomition, 'The law cannot change a fact'?
Surely the same is true of language, see below.

No "facts" are being changed.

What error do you imagine that the ancient tribesmen of the British
Isles made when they added the word "weight" to Old English over 1000
years ago, with the meaning of a quantity measured with a balance? A
word they used for measuring how much stuff they had, for purposes of
commerce? Something which you admitted yourself, up above, SHOULD BE
mass, and that's exactly what they measured with those balances?

Was the error that these heathens were unable to figure out the
God-given word they were supposed to invent for this purpose?

There was no error then. There is no error today when we use the very
same word "weight," with the very same meaning, for the very same
purposes.

It is, in fact the original meaning of the word weight, which entered
Old English over 1000 years ago meaning the quantity measured with a
balance. That quantity is, of course, mass--not force due to gravity.

A thousand years ago the contemporary known models for gravity were
too primitive to distinguish between the two. Thus when the pound
was defined as a unit of weight it was simultaneously defined
as a unit of mass and of force, and for that matter, of space-
time distortion. those folks didn't realize that but that's
doens't change the facts.

The pound was never used to measure force before the 17th century, at
least. It was never a well-defined unit of force before the 20th
century. It doesn't have an "official" definition as a unit of force
even today in the 21st century.

Those balances were, of course, the only weighing devices anybody had
ever used even 200 years ago, and people had been weighing things for
something like 7000 years or more before then.

Balances of course, are mass comparison devices. When one 'weighs'
something with a balance, or for that matter, by any other method,
and announces it weighs x pounds it is ambiguous, and also usually
unimportant whether that person means weight or mass.

Indeed, I used the example of telling you I weigh 165 pounds.
That tells you how much there is of me without regard to whether
I meant pounds force or pounds mass. Were I on the moon, you might
need clarification.


What you need to do is to take a look at how the standards for a pound
were propogated throughout the world.

I don't see that I need to do that at all.

Sure, your other option is to remain stupid.

If someone made a copy of the
standard maintained at London, and took it to South Africa or to
ashington, D.C. or whereever, what exactly is it that is the same
about the pound in the new location? It exerts a different amount of
force in the new location, but it is still the same mass.

Maybe you should take a look at what the experts in the field have to
say about it, people such as the keepers of our standards. For
example, the national standards laboratories of the United Kingdom and
of the United States:

Here's a FAQ by the NPL, the national standards laboratory of the
U.K.:
http://www.npl.co.uk/force/faqs/forcemassdiffs.html

Weight
In the trading of goods, weight is taken to mean the
same as mass, and is measured in kilograms. Scientifically
however, it is normal to state that the weight of a
body is the gravitational force acting on it and hence
it should be measured in newtons, and this force
depends on the local acceleration due to gravity.

See? I'm right.

About which of those two definitions?

To add to the confusion, a weight (or weightpiece)
is a calibrated mass normally made from a dense
metal, and weighing is generally defined as a
process for determining the mass of an object.

So, unfortunately, weight has three meanings
and care should always be taken to appreciate
which one is meant in a particular context.


Note--they clearly refer to different *meanings* of this word.

So it makes perfect sense that since 'weight' is ambiguous as to
whether it means force or mass a standard unit of weight, the
pound, is also ambiguous as to whether it means force or mass

That is somewhat time-dependent. But no, one doesn't follow from the
other at all. You could easily have an ambiguous word weight,
measured in newtons for some of its meanings, and measured in
kilograms, even in a world where kilograms were never used as units of
force.

Before pounds force were ever well defined, we had a well-defined
English unit of force: the poundal.

That IS just what I wrote befor, pounds are ambiguous, slugs
are not. Can you get that through YOUR thick skull?

No, you went beyond that, and claimed that pounds force came first.

Here's NIST, the U.S. national standards agency, in their Guide for
the Use of the International System of Units, NIST Special Publication
811,
http://physics.nist.gov/Pubs/SP811/sec08.html

In commercial and everyday use, and especially in common
parlance, weight is usually used as a synonym for mass.
Thus the SI unit of the quantity weight used in this
sense is the kilogram (kg) and the verb "to weigh" means
"to determine the mass of" or "to have a mass of".

Examples: the child's weight is 23 kg
the briefcase weighs 6 kg
Net wt. 227 g

Note especially that last one--this is the proper usage for the sale
of chicken.

The National Standard of Canada, CAN/CSA-Z234.1-89 Canadian Metric
Practice Guide, January 1989:

5.7.3 Considerable confusion exists in the use of the
term "weight." In commercial and everyday use, the
term "weight" nearly always means mass. In science
and technology, "weight" has primarily meant a force
due to gravity. In scientific and technical work, the
term "weight" should be replaced by the term "mass"
or "force," depending on the application.

5.7.4 The use of the verb "to weigh" meaning "to
determine the mass of," e.g., "I weighed this object
and determined its mass to be 5 kg," is correct.

Again, you prove that I was correct to say that pounds are ambiguous
and can be either pound force or pound mass. I was already convinced
of that a long time ago. You do not need to keep proving that I
was right.

Too stupid to even keep straight what we are dealing with. Here we
are dealing with the ambiguities of the word "weight," not ambiguities
in different units being called pounds.

Pounds are also ambiguous even if you limit them to the mass units,
and even if "weight' is never used as a synonym for mass: we have the
avoirdupois pounds, the troy pounds, other old British units such as
the tower pound and the pound trone, the 500 g pounds still used in
various parts of the world, and the hundreds of other pounds that
those 500 g pounds replaced back in the 19th century.

Furthermore, even if "weight" were not ambiguous, and never a synonym
for mass, we still would have the ambiguity in pounds as both units of
mass and units of force.

The thing to note here is the different treatment of the noun forms
and the verb forms, Contrast the application dependent meanings of
the former with the unqualified "is correct" in the latter.

Huh?

Go take remedial English and learn what a noun and a verb are.

The other thing to note is that "nearly always" is much stronger than
"primarily"--they even got that part correct.

Like the experts tell you, you are best off avoiding the word "weight"
in a technical context, and if you do use it, you need to make clear
which meaning is intended.


In most applications the ambiguity, if present, is unimportant. For
example, if I am to design a bridge to support 200,000 pounds of traffic
it matters not whether the pounds in that specification are pounds
force or pounds mass so long as the bridge is to be built near the
Earth's surface. As to that variation in the acceleration due to
gravity that worries you so, don't sweat it that's why we use
fators of safety.

If I refer to pressure in psi it is understood that I mean pounds force
becuase pressure if force per unit area.

And if I refer to 100 pounds of hydrazine in a fule tank on a
spacecraft it is clear that I mean pounds mass. (Though I'd rather
use slugs, it makes the calculations easier.)

E.g. in your researches, what is the earliest definion of pound that
you can find?

Long before there was an England.


Which was also long before anyone had enunciated theory of gravity
of sufficient complexity to allow one to differentiate, linguistically
between mass and weight.

We can, however, determine today what they measured then.

We do know what they would have wanted to measure, if they had made
these distinctions. After all, we measure the same thing today for
the same purposes.

What they measured and what they wanted to measure are in total
agreement. So there is no room for you to claim this ambiguity in
ancient times--that only shows up after we start getting engineers in
the modern sense.

I will add, at the risk of causing you a stroke, that the distinction
between mass and weight exists regardless of the language being used
or even if language exists at all. Should we all be struck dumb,
we would not simultaneously become weightless.

Quite the contrary, this problem is very much a language specific
problem, one that English shares with some other languages such as
French. But it doesn't have to be that way.

For example, when physicists using the Norwegian language were
shopping for a word to use in their jargon for the same things for
which those using English use "weight," they did not choose "vekt"
(various spellings such as vikt, wægt, etc. over time), which is the
cognate of "weight" in English. Instead, they choose an entirely
different word, "tyngde." So Norwegian doesn't have the same
ambiguities that English has.

You can't get a much better indication that the only science involved
here is linguistics, can you?

In case any speaker of the Scandinavian languages sees this, see
Aschehougs Konversasjons Leksikon, H. Aschehoug & Co. (W. Nygaard),
Oslo, Norway, femte utgave, 1972. [No, the publisher is not related
to me, and some of the words were cut off on the photocopy I have so
some letters are replaced by ?]

Vekt (mlt.). 1. Instrument til veiing, se Veieredskaper.
2. Dss. tyngde (s.d.) el. gravitasjon, den kraft et lege øver mot
underlaget når det holdes i likevekt. I daglig brukes v. også ofte i
betydningen masse (s.d.) for å a??? mengden av et stoff. For p unngp
denne tvetydighet bru??? man i fysikken helst ikke betegnelsen v., men
masse og tyngde. Spesifikk vekt, dss. spesifikk tyngde, tyngde pr.
volumen??? tidligere som regel brukt i betydningen tetthet (s.d.) el.
??sitet, masse pr. volumenhet.

Tyngde kalles den kraft som er opphav til den lokale
tyngdeakselerasjon, dvs. til den akselerasjon et legeme får i forhold
til jorden når det faller fritt og uten luftmotstand under påverkning
av Jordens gravitasjonsfelt (tyngdefelt). T. skal angis i et
koordinatsystem som følger Jorden i dens rotasjon, og den blir lik
summen av den lokale gravitasjon og den lokale sentrifugalkraft
(s.d.). Den varierer derfor fra sted til sted. Se Gravitasjon. -- T.
virker på hvert enkelt massepunkt i et legeme, men kan tenkes sat
sammen til en resultantkraft, som er lik summen av tyngden til hvert
enkelt punkt, og som angriper legemet i massemiddelpunktet (s.d.) el.
tyngdepunktet. -- T. brukes også synonymt med gravitasjon.

end quote

The same is true in some of the Eastern European languages, according
to what someone told me in another newsgroup a long time ago. I don't
remember the specific language involved then, maybe Hungarian or
Bulgarian or something like that.



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

Gene Nygaard wrote in message . ..
On 12 Dec 2003 09:05:15 -0800, (Fred the Red
Shirt) wrote:

[I probably snipped a bit too much. If the proper attribution is
unclear, just go back to the earlier articles.]


What you address here is an vagueness in human language, not an
ambiguity in natural law.

Good grief. What in the world do you think we've been talking about.
Of course, it is linguistics.

Evidently that is what you have been talking about, not I.

I thought this was clear, but let me carify it now. When I refer
to weight, without modifier, I refer to weight as defined by
Newton's Law of Gravitation and that definition can be written
thus:

W = Gp * (m) / (r^2) Where Gp = G * mp.

G is the gravitational constant
mp is the mass of the planet to which the weight is referred
m is the mass of the body whose weight is in question
r is the distance from that body to the center of mass of
the planet in question (assume a spherical cow, er planet)
* is multiplication
/ is division
^ is exponentiation
2 is an integer greater than one but less than 3
W is then the weight of that body.

One could define weight using different symbols and explain those
symbols in a different language and that would be the SAME definition
of weight, not a different one because scientific definitions are
conceptual, not linguistic.



What's really strange is that there are always some fools who will
insist that when we buy and sell goods by weight, we'd want to measure
some quantity that varies with location. How stupid can some people
be?

I never found any who wanted to do that, nor anyone who does
because on a practical level wherever the measurement is made,
even if it is made by actually measuring force, the variance
is so small that most normal folks consider in negligible, or
rather it IS so negligible that no one has any reason to consider
it at all. I'll be damned if I can understand why you find that
miniscule variance to be so disconcerting.

It is a whopping 0.53%, even if you limit yourself to SEA LEVEL.

Throw in Mt. Chimborazo, the highest mountain on Earth, and it gets
close to 3/4 of a percent; more than 1 part in 140.

Now, if you have a standard 400 oz t bar of platinum, do you suppose
it would make a difference if they were units of force rather than
units of mass? Would three ounces at $600/oz matter?

I sincerely doubt that I shall ever be trading in precious metals
let alone doing so at the summit of Mt Chimborazo. I repeat that
for most folks any difference that results from neglecting the
issue is insignificant.



Get it through your thick skull that "weight" is an ambiguous word,

I understood that already and am quite prepared to explain it.

In Newtonian Physics, 'weight' is a force. Mass OTOH is the factor of
proportionality between force and acceleration.

In General Relativity, 'weight' is a geometrial distortion of
space-time due to the presence of mass.

So weight is either a force or a geometrical effect, depending on
which model you happen to be using at the time.

Those models only explain weight AFTER you have chosen to define it as
the effect of gravity.

They do not 'explain' weight. They define weight.

If it [the pound] was
defined as a unit of weight then it was simultaneously defined as
a unit of force without regard to whether or not the person(s)
defining it UNDERSTOOD that they were doing so.

Bull****.

The meaning of "weight" which is a synonym for "mass" in physics
jargon

Can you state the formal name any internally consistant physical
theory in which weight and mass are synonyms? As illustrated above,
that is true of neither Newtonian Physics, nor General Relativity.

There are different quantities involved here. But there is no
"natural law" which tells you what word you should be using for any of
them.

Agreed.


You can choose to call a certain quantity "weight." Your doing so,
however, does not magically erase other meanings which the word
already had.

Nor do those other meaning prevent you from using that same word
to represent a different concept. It is those concepts I discuss
using (or at any rate attempting to use) language to discuss
those, rather than simply dicussing the language with no regard
for concept.


I know of no physical theory, nor any physicist that uses the words
weight and mass interchangeably within the discipline of physics
itself.

In the first place, what in the world gave you the idea that what
physicists do has anything whatsoever to do with "baggage weight"?

Nothing. I was refering back to your statement:

'The meaning of "weight" which is a synonym for "mass" in physics jargon'


In the second place, it isn't true. Ever heard of atomic weight?
Molecular weight?

Those are not weights. That the word weight appears in those terms
does not make them weights any more than the use of the word force
in the term 'corriolis force' makes it a force.


Do you remember the days when atomic weight in physics was different
from atomic weight in chemistry? When one of them defined it based on
oxygen-16 being 16.0000, and the other defined it based on the natural
mix of oxygen isotopes being 16.00000?

No, I learned the formal defintion of the mole after it had been
restated based on C-12.


is quite proper and legitimate, well justified in history and
in linguistics and in the law.

Have you never heard the adhomition, 'The law cannot change a fact'?
Surely the same is true of language, see below.

No "facts" are being changed.

My point exactly.

Back to your boheaded pedantistic statement that so many authors
have 'got it wrong' (my paraphrase) when they define the pound
mass to be the mass of an object that weighs one pound. Surley
a liguist such as yourself has sufficient cunning to understand
that authors of textbooks often nay, typically employ esotheric
defintions of terms in common usage for the the purposes of the
curriculum. Thus if within that curriculum the pound force is
defined first then the pound mass may be defined as the mass
of an object which weighs one pound.

Now mind you, I never had a course nor saw a text that actually
bothered to formally define either the pound mass or the pound
force. My physics texts only dealt with formal defintions of
SI units and my engineering texts generally assumed a practical
understanding of units of measure.

But in what order an author chooses to introduce units and
therfore which are derivative of the others may be based,
or dare I say SHOULD be based on the approach the author wishes
to take in teaching the material in question. An engineering
text or physics text is not a text in the history of commerce,
in the history of the standardization of units of measure by
government burocracies, nor of lingusitics and the author need
not slavishly adhere to such histories or histrionics so long
as the bridges designed by his students do not collapse.

These texts are not 'wrong'. Your arguemtn would only show
show them to be wrong if they attributed the author's defintion's
to a standards organisation.


Here's a FAQ by the NPL, the national standards laboratory of the
U.K.:
http://www.npl.co.uk/force/faqs/forcemassdiffs.html

Weight
In the trading of goods, weight is taken to mean the
same as mass, and is measured in kilograms. Scientifically
however, it is normal to state that the weight of a
body is the gravitational force acting on it and hence
it should be measured in newtons, and this force
depends on the local acceleration due to gravity.

See? I'm right.

About which of those two definitions?

About the ambguity. There are TWO defintions.



That IS just what I wrote befor, pounds are ambiguous, slugs
are not. Can you get that through YOUR thick skull?

No, you went beyond that, and claimed that pounds force came first.

No I claimed that the pound mass could be losely defined based on
the pound force. That is true. I can define pound force first and
pound mass second, as perhaps is done is some texts or more importantly,
I can assume that the reader is famliar with the pound force and not
the pound mass and thus inform the reader that the pund mass may be
define loosely, as the mass of an object that weighs one pound.



What they measured and what they wanted to measure are in total
agreement. So there is no room for you to claim this ambiguity in
ancient times--that only shows up after we start getting engineers in
the modern sense.

I agree that in ancient times the issue was one of vagueness, not
ambiguity.


I will add, at the risk of causing you a stroke, that the distinction
between mass and weight exists regardless of the language being used
or even if language exists at all. Should we all be struck dumb,
we would not simultaneously become weightless.

Quite the contrary, this problem is very much a language specific
problem, one that English shares with some other languages such as
French. But it doesn't have to be that way.

I'll stick to my statement that depriving us of language will not
render us weightless.


For example, when physicists using the Norwegian language were
shopping for a word to use in their jargon for the same things for
which those using English use "weight," they did not choose "vekt"
(various spellings such as vikt, wægt, etc. over time), which is the
cognate of "weight" in English. Instead, they choose an entirely
different word, "tyngde." So Norwegian doesn't have the same
ambiguities that English has.

You can't get a much better indication that the only science involved
here is linguistics, can you?

I suppose linguistics is a 'science' in the same sense as library
science, political science or (shudder) computer science. And,
yes, I agree that your arguments are entirely linguistic.

--

FF