RV-7a baggage area

Gene Nygaard wrote in message . ..
On 9 Dec 2003 10:34:34 -0800, (Fred the Red
Shirt) wrote:

Russell Kent wrote in message ...


I'm sorry, you're correct. I didn't mean to imply that they are the only unit of
mass. I was taught (perhaps incorrectly) that the unambiguous term for weight
(scientific meaning) in the English system was "slugs". Apparently it's also
"pounds force" now (it may have been them, too, and I've just forgotten it).

I think you mistyped. 'Slugs' are unambiguously a unit of mass.

Pounds are ambiguously a unit of force. Ambiguity exists because it
is popular in some disciplines to use a unit of mass defined (loosely)
as that mass which weighs one pound.

But you knew that.

Well, now, in this fuzzy dreamworld you inhabit, what exactly is the
standard for a pound?


HFC? In what fuzzy dreamworld that you inhabit is a slug ambiguous
but the pound is not?

If I say that I weigh 165 lbs (I'd be lying but that's not relevent)
it is ambiguous if I mean pounds force or pounds mass. But if I
say that atmospheric pressure at sea level is 14.7 psi then I
unabiguously mean pounds force per square inch because pressure is
force per unit area.

If I say that I dropped a 15 slug rock on my foot that unambiguously
implies mass.

Is that really so hard to understand?

--

FF

On 10 Dec 2003 06:50:50 -0800, (Fred the Red
Shirt) wrote:

Gene Nygaard wrote in message . ..
On 9 Dec 2003 10:34:34 -0800, (Fred the Red
Shirt) wrote:

Russell Kent wrote in message ...


I'm sorry, you're correct. I didn't mean to imply that they are the only unit of
mass. I was taught (perhaps incorrectly) that the unambiguous term for weight
(scientific meaning) in the English system was "slugs". Apparently it's also
"pounds force" now (it may have been them, too, and I've just forgotten it).

I think you mistyped. 'Slugs' are unambiguously a unit of mass.

Pounds are ambiguously a unit of force. Ambiguity exists because it
is popular in some disciplines to use a unit of mass defined (loosely)
as that mass which weighs one pound.

But you knew that.

Well, now, in this fuzzy dreamworld you inhabit, what exactly is the
standard for a pound?


HFC? In what fuzzy dreamworld that you inhabit is a slug ambiguous
but the pound is not?

If I say that I weigh 165 lbs (I'd be lying but that's not relevent)
it is ambiguous if I mean pounds force or pounds mass. But if I
say that atmospheric pressure at sea level is 14.7 psi then I
unabiguously mean pounds force per square inch because pressure is
force per unit area.

If I say that I dropped a 15 slug rock on my foot that unambiguously
implies mass.

Is that really so hard to understand?

No argument about those points.

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. Pounds
have always been units of mass, and they are now, since a 1959
international agreement, defined around the world as 0.45359237 kg
exactly. See the current U.S. law, and a discussion of the prior U.S.
definition as a slightly different exact fraction of a kilogram for 66
years before then, and a discussion of the international agreement at
one of these sites (same document):
http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf
http://gssp.wva.net/html.common/refine.pdf

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.

It is pounds force which were never well defined before the 20th
century. It is pounds force which don't even have an official
definition today.


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

Fred the Red Shirt wrote:

Russell Kent wrote in message ...


I'm sorry, you're correct. I didn't mean to imply that they are the only unit of
mass. I was taught (perhaps incorrectly) that the unambiguous term for weight
(scientific meaning) in the English system was "slugs". Apparently it's also
"pounds force" now (it may have been them, too, and I've just forgotten it).

I think you mistyped. 'Slugs' are unambiguously a unit of mass.

Oy. You are correct, sir.

Pounds are ambiguously a unit of force. Ambiguity exists because it
is popular in some disciplines to use a unit of mass defined (loosely)
as that mass which weighs one pound.

But you knew that.

Ibid. :-)

Russell Kent

Gig Giacona wrote:

Hint: The cables or straps were tie downs.

Another hint. On RVs, the cables that run from the
seat backs to the upper part of the baggage area
are part of the shoulder harnesses.

Dave 'no-load' Hyde

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.


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

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

--

FF

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.

It was after you brought it up, saying: "Ambiguity exists because it
is popular in some disciplines to use a unit of mass defined (loosely)
as that mass which weighs one pound."

In actual fact, pounds are defined very specifically as 0.45359237 kg
exactly. You don't get there by starting with a pound force. You can
use that definition, in conjunction with some value for a standard
acceleration of gravity (and none has ever been officially adopted for
this purpose, so there are a few different values which are used for
this), to define a pound force.

If your confusion about this were an isolated problem suffered by you
individually, it would hardly be worth comment. But the fact of the
matter is that this confusion is also shared by several authors of
physics textbooks, and many science teachers at various levels. You
could easily find textbooks and web sites making the same claims that
you made, many not merely implying but specifically stating that
pounds mass are a substandard derivative of the pound as a unit of
force--there is in fact widespread, systematic miseducation on this
point.

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.

No. Russell Kent originally claimed that pounds ARE NOT units of
mass. As he did so, he claimed that slugs are the English units of
mass.

Then later, after he learned that pounds are indeed units of mass, as
well as pounds force, he got confused about what slugs are. He then
twice claimed that slugs are units of force.

But he never called slugs ambiguous nor implied that slugs are
ambiguous. He never claimed, in either message, that slugs could be
both units of mass and units of force. He was just confused in the
second message. So it is fine that you called him on that, and
pointed out that he was wrong--but in the process, you introduced a
new issue about the "looseness" of the definition of a pound as a unit
of mass.

Gene Nygaard

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.


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

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

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."

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.

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'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?

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

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

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.

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.

What you need to do is to take a look at how the standards for a pound
were propogated throughout the world. If someone made a copy of the
standard maintained at London, and took it to South Africa or to
Washington, 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.
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.

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.

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.

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.

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

Long before there was an England.

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

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. .

"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."

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.

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'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?

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

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

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.

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.

What you need to do is to take a look at how the standards for a pound
were propogated throughout the world. If someone made a copy of the
standard maintained at London, and took it to South Africa or to
Washington, 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.
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.

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.

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.

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.

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

Long before there was an England.

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

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.


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.



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.

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.

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

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.


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.


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.


If someone made a copy of the
standard maintained at London, and took it to South Africa or to
Washington, 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.

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


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.


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?


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.

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.

--

FF

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.

It was after you brought it up, saying: "Ambiguity exists because it
is popular in some disciplines to use a unit of mass defined (loosely)
as that mass which weighs one pound."

Which is entirely true.


In actual fact, pounds are defined very specifically as 0.45359237 kg
exactly.

Which I'll also assume is entirely true (Unless we want to
quibble as to the distinction between dfining a unit of measure
and determining the standard value for that unit, which will
turn on how one defines 'definition'.)

But I would hardly call that a loose definition. If you prefer,
I can elaborate on teh meaning of loose defintion by pointing out
that loosely speaking, pounds mass and pounds force may be circularly
defined.

The pound mass is a mass with a weight of one pound and the pound
force is weight of a one pound mass within the context of weight as
force. We could quibble about where you measure the gravitational
acceleration but then we wouldn't be defining things loosely, would
we.

Now, to establish a standard value for either unit one can use,
a more formal version of at most only one of those defintions.

You don't get there by starting with a pound force. You can
use that definition, in conjunction with some value for a standard
acceleration of gravity (and none has ever been officially adopted for
this purpose, so there are a few different values which are used for
this), to define a pound force.

I think you are confusing definition with standardization. One
can define one thing in terms of anther and vice-versa without
need to state any way to determine a standard value for either.


If your confusion about this were an isolated problem suffered by you
individually, it would hardly be worth comment.

There was no confusion on my part.

You, OTOH, are confabulating defintion, standardization, jargon,
ligusitics, law, pedantry and god knows what else for no apparent
purpose.


But the fact of the
matter is that this confusion is also shared by several authors of
physics textbooks, and many science teachers at various levels. You
could easily find textbooks and web sites making the same claims that
you made, many not merely implying but specifically stating that
pounds mass are a substandard derivative of the pound as a unit of
force--there is in fact widespread, systematic miseducation on this
point.

I have found pounds mass to be a poor choice of units for purposes
of most calculations. I prefer to use the slug which is unambiguously
a unit of mass.

If one works first with pounds force, later with pounds mass, then one
is introduced to pounds mass as deriviative of pounds force. Again,
it matters not how the MBS determines the standard value for either.


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.

No. Russell Kent originally claimed that pounds ARE NOT units of
mass. As he did so, he claimed that slugs are the English units of
mass.

I'm not going to check to see if he wrote that or not since that is
not what caught my eye. I'll confirm that he wrote this:

In
http://groups.google.com/groups?hl=e...0ti.com&rnum=4
Russel Kent wrote:

I was taught (perhaps incorrectly) that the unambiguous term for
weight
(scientific meaning) in the English system was "slugs".

...
But he never called slugs ambiguous nor implied that slugs are
ambiguous.

Ok, he referred to slugs as the unambiguos term (not unit) for (not
of)
weight. Which not possible given that weight itself is an ambiguous
term, though not in phyusics in which weight it usually defined by
Newtons law of gravitational attraction.

But you seem to think that it is incorrect to loosely define a thing
if that definition does not strictly follow in a linear fashion, from
a published standard.

If one only defines things in a manner that strictly follows in a
linear fashion from a published standard how could one ever define
a thing 'loosely?'

--

FF