Gene Nygaard wrote:
Apparently Halliday and Resnick were a lot smarter a couple of decades
earlier, when they were only a little past their prime:

Hey Gene,

Maybe Halliday and Resnick in fact _avoided_ becoming "past their prime"
when they adapted their point of view to the one which now prevails.

73, Jim AC6XG

On Fri, 26 Sep 2003 10:05:08 -0700, Jim Kelley
wrote:



Gene Nygaard wrote:
Apparently Halliday and Resnick were a lot smarter a couple of decades
earlier, when they were only a little past their prime:

Hey Gene,

Maybe Halliday and Resnick in fact _avoided_ becoming "past their prime"
when they adapted their point of view to the one which now prevails.

It isn't a matter of "point of view." This isn't politics or an
opinion poll, and it isn't psychology or sociology, and it isn't
freshman literature. It's a matter of facts--of standards and
definitions. The fact is that pounds are units of mass, and that
pounds force also exist (a recent *******ization, of course).

Their 1981 Appendix misstates those facts. That's it, plain and
simple.

Now prevails? I issue you the same challenge I issued to our
Metrologist:

Show me an official definition of a pound force on the NIST pages.
Bet you can't do so. Note that a conditional definition, with a big
"if", indicating that this is only one possible acceptable definition,
is not sufficient--I want an official definition.

If you can't do that, try a broader problem: Show me an official
definition of a pound as a unit of force from ANY law of ANY country
in the world, or from ANY standard of ANY national or international
standards organization, or from ANY standard of ANY professional
organization.

Halliday and Resnick were right on top of things in 1960, already
aware of the change of definition that had taken place only 1 July of
the previous year, effective immediately on its publication. If you
haven't read what the National Bureau of Standards said in that
announcement, take the time now to do so (partial excerpt below).
http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf
http://gssp.wva.net/html.common/refine.pdf

Announcement. Effective July 1, 1959, all calibrations in
the U.S. customary system of weights and measures carried
out by the National Bureau of Standards will continue to be
based upon metric measurement standards and except for
the U.S. Coast and Geodetic Survey as noted below, will be
made in terms of the following exact equivalences and
appropriate multiples and submultiples:
1 yard = 0.9144 meter
1 pound (avoirdupois) = 0.453 592 37 kilogram

Currently, the units defined by these same equivalences,
which have been designated as the International Yard and
the International Pound, respectively, will be used by the
National Standards Laboratories of Australia, Canada, New
Zealand, South Africa, and United Kingdom; thus there will
be brought about international accord on the yard and
pound by the English-speaking nations of the world, in
precise measurements involving these basic units.

Now, perhaps you think something changed between 1960 and 1981 when
the revised Halliday & Resnick came out. What would that have been?
Some change in the law? In the standards kept by the National Bureau
of Standards (later replaced by NIST)? Show me some justification for
a change, some change in facts, that would justify a different "point
of view" as you put it.

Or were Halliday and Resnick just terribly prescient, and they foresaw
some change that took place between 1981 and today? If so, tell us
exactly what that change was.

Or maybe you think that the 1959 redefinition is just some sort of
"legal definition" and that in the sciences we have some other "real
definition" that we go by. Is that your position? No problem if it
is, but if that is indeed what you are claiming, please fill us in on
a few followup questions:

1. What is the nature of the standard for a pound in its "scientific
definition"? Is it something mechanical, something electrical, or
what?

2. Who declared whatever the standard is to be the standard? NIST?
U.S. Congress? ISO? BIPM? The First International Extraordinary
Hydrographic Conference (they are the ones who defined the standard
for the international nautical mile)? Some other entity?

3. When was it made the standard? Just the year will do.

4. To whom does the standard apply? In other words, for whom does
the defining agency have the authority to make the standards?

5. Along the same lines, if this is a "scientific definition" which
differs from the "legal definition," what is its scope? What is "in
science"? Does it include Halliday and Resnick's definition of a Btu,
and their use of units of Btu/(lb °F) for specific heat capacity?
Same for Sears and Zemansky, the textbook cited by the Peacekeeper
Engineer?

6. What is the exact relationship between pounds force and the metric
units, or the relationship to the greatest precision in which it can
be expressed if it is not exact?

7. Even if all this were true, would it mean that the pound is a unit
of mass? Is there some rule that says that textbook authors are
allowed to bury their heads in the sand, and ignore the real world
which does in fact use the definition agreed on by those six national
standards laboratories of some of the most advanced nations in the
world in 1959?


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

Gene Nygaard wrote:
Now, perhaps you think something changed between 1960 and 1981 when
the revised Halliday & Resnick came out.

Hi Gene,
You'll be surprised to learn that a lot has changed since 1960.

Show me some justification for
a change, some change in facts, that would justify a different "point
of view" as you put it.

Since it's apparent that you have no need to change your point of view,
I find that I likewise have no need to change your point of view.

Why do you think torque wrenches have the unit 'foot-pounds' printed on
them if the pound is a unit of mass?

2. Who declared whatever the standard is to be the standard?

I don't know, but I guess they should have spoken to you about it
first. ;-)

4. To whom does the standard apply?

It applies to everyone except the people who apparently don't want it to
apply to them. :-)

6. What is the exact relationship between pounds force and the metric
units, or the relationship to the greatest precision in which it can
be expressed if it is not exact?

It's not like it's a big secret or anything.

7. Even if all this were true, would it mean that the pound is a unit
of mass?

The pound is generally accepted to be a unit of force. Otherewise,
they'd have to get rid of all the PSI pressure gauges.

Is there some rule that says that textbook authors are
allowed to bury their heads in the sand, and ignore the real world
which does in fact use the definition agreed on by those six national
standards laboratories of some of the most advanced nations in the
world in 1959?

It really wouldn't hurt you to pick up a (modern) physics book and just
look at it some time. Or maybe you're of the opinion that all modern
physics books are wrong?

But here's a question: if one pound of mass weighs one pound and exerts
one pound of force, given F = MA, what are the units of A (little g)?
Or, would you claim one pound of mass actually weighs 32.17 pounds?

73, Jim AC6XG

On Fri, 26 Sep 2003 15:44:09 -0700, Jim Kelley
wrote:

Gene Nygaard wrote:
Now, perhaps you think something changed between 1960 and 1981 when
the revised Halliday & Resnick came out.

Hi Gene,
You'll be surprised to learn that a lot has changed since 1960.

Show me some justification for
a change, some change in facts, that would justify a different "point
of view" as you put it.

Since it's apparent that you have no need to change your point of view,
I find that I likewise have no need to change your point of view.

Why do you think torque wrenches have the unit 'foot-pounds' printed on
them if the pound is a unit of mass?

Mine also has "meter kilograms" on it. What does that tell you?

Note that I've said all along that pounds force exist as well. I've
just been attacking the idiots who claim that pounds are never units
of mass.

2. Who declared whatever the standard is to be the standard?

I don't know, but I guess they should have spoken to you about it
first. ;-)

Did anybody do so?

Missed that part, didn't you!

4. To whom does the standard apply?

It applies to everyone except the people who apparently don't want it to
apply to them. :-)

6. What is the exact relationship between pounds force and the metric
units, or the relationship to the greatest precision in which it can
be expressed if it is not exact?

It's not like it's a big secret or anything.

7. Even if all this were true, would it mean that the pound is a unit
of mass?

The pound is generally accepted to be a unit of force. Otherewise,
they'd have to get rid of all the PSI pressure gauges.

And what about Btu's? Specific heat capacities in Btu/(lb °F)?

Is there some rule that says that textbook authors are
allowed to bury their heads in the sand, and ignore the real world
which does in fact use the definition agreed on by those six national
standards laboratories of some of the most advanced nations in the
world in 1959?

It really wouldn't hurt you to pick up a (modern) physics book and just
look at it some time. Or maybe you're of the opinion that all modern
physics books are wrong?

But here's a question: if one pound of mass weighs one pound and exerts
one pound of force, given F = MA,

There's your error, a faulty premise.

All we really know is that force is proportional to mass times
acceleration. One way we can express this is F = k·m·a. Yes, we can
choose our units so that the proportionality constant is one, but we
don't have to do so. In any case, the k, whether it is 1 or some
other number, is always the same for a particular choice of units for
those three quantities.

Also, when we do choose our units that way, we have several different
ways we can do so using English units, as well as several ways we can
do so using metric units (only one of which is SI, the modern metric
system).

what are the units of A (little g)?
Or, would you claim one pound of mass actually weighs 32.17 pounds?

A pound of mass at sea level on Earth exerts a force of 32.088
poundals and 32.258 poundals (not pounds force). It will exert a
force of something like 32.024 poundals atop Mt. Chimborazo, the
highest mountain on Earth (at least in both ways relevant to this
example). It exerts a force of somewhere between 0.9973 lbf and
1.0026 lbf at sea level.

--
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
"It's not the things you don't know
what gets you into trouble.

"It's the things you do know
that just ain't so."
Will Rogers

I am 240 pounds 'mass' on earth. That's a fact.

I am 240 pounds 'mass' on moon. That's a weird assertion!

If that assertion is true, who changed the density of the moon??

Dave Shrader wrote:
"If that assertion (I am 240 pounds "mass" on earth. That`s a fact. I am
240 pounds "mass" on moon. That`s a weird assertion!) is true, who
changed te density of the moon??"

Mass is the bulk of matter though not necessarily equal to its weight. A
mass weighing 240 pounds on earth weighs less on the moon because there
is less mutual attraction between the moon, of much smaller mass than
the earth`s mass, and the object which weighs 240 pounds on the earth.

Mass is the property which provides a body with inertia. Mass is the
mechanical analogy of inductance. Mass is equal to the weight of a body
divided by the acceleration due from gravity (32ft./sec./sec.). This is
an expression of Newton`s 2nd law of motion: F = MA, thus M = F/A.

Newton`s 1st law says that to move a body at rest, enough force must be
applied to overcome its inertia.

Newton`s 3rd law says that for every action there is an equal and
opposite reaction.

The gravitational force of the earth is stated as "1". The gravitational
force on the moon is about 0.16 that on earth, so an object weighing 240
pounds on earth would weigh only 38.4 pounds on the moon.

Best regards, Richard Harrison, KB5WZI

(Richard Harrison) wrote in message ...
Dave Shrader wrote:
"If that assertion (I am 240 pounds "mass" on earth. That`s a fact. I am
240 pounds "mass" on moon. That`s a weird assertion!) is true, who
changed te density of the moon??"

Mass is the bulk of matter though not necessarily equal to its weight. A
mass weighing 240 pounds on earth weighs less on the moon because there
is less mutual attraction between the moon, of much smaller mass than
the earth`s mass, and the object which weighs 240 pounds on the earth.

Mass is the property which provides a body with inertia. Mass is the
mechanical analogy of inductance. Mass is equal to the weight of a body
divided by the acceleration due from gravity (32ft./sec./sec.). This is
an expression of Newton`s 2nd law of motion: F = MA, thus M = F/A.

Newton`s 1st law says that to move a body at rest, enough force must be
applied to overcome its inertia.

Newton`s 3rd law says that for every action there is an equal and
opposite reaction.

The gravitational force of the earth is stated as "1".

Not really; the standard acceleration due to gravity (more accurately,
of free fall), or an approximation of the local acceleration, is
sometimes expressed as 1 lb/lbf, or 1 kgf/kg, or 1 gee. But it isn't
dimensionless, and it is also often expressed with units in which its
numerical value is not one (always, if you are using SI units, the
modern metric system).

The gravitational
force on the moon is about 0.16 that on earth, so an object weighing 240
pounds on earth would weigh only 38.4 pounds on the moon.

That's certainly true enough, at least for one definition of weight.
But it has nothing to do with Dave Shrader's "I am 240 pounds "mass"
on moon. That`s a weird assertion!" You are talking about something
different from mass.

Gene Nygaard

Gene Nygaard wrote:
"You are talking about something different from mass."

Yes. An orbiting astronaut may be weightless due to a particular balance
of forces, but he has mass and inertia.

We have weight and force. Either weight or force may be expressed in
pounds or kilograms. The conversion number I remember and use is: 2.2
pounds equal 1 kilogram.

The dictionary says the kilogram is a unit of mass, since a mass can
conveniently be accurately represented by an object. That particular
object is a cylinder of platinum-iridium alloy, called the international
prototype kilogram. This object is preserved in a vault at Sevres,
France.

Work may be meaasured as force times distance or as pounds times feet.
Power is work per unit time. Power may be expressed as foot-pounds per
minute. James Watt`s horse was said capable of working at a rate of
33,000 foot-pounds per minute. I calculate that as 250 kilogram-feet per
second or 76.2 kilogram-meters per second.

Best regards, Richard Harrison, KB5WZI

On Sat, 27 Sep 2003 11:48:24 GMT, Dave Shrader
wrote:

I am 240 pounds 'mass' on earth. That's a fact.
No, in the US system of measurement your mass is measured in slugs.
your weigh is measured in pounds and is 240# on earth

In the metric system mass is in kg. Again the metric system is easier.
240#=109.091 kg

I am 240 pounds 'mass' on moon. That's a weird assertion!

Your mass is still the same (109.091 kg), but your weight is
considerably less on the moon.


If that assertion is true, who changed the density of the moon??

It has nothing to do with the assertion, but the mass of the moon is
less than the mass of the earth.

The mass of you and the earth sets what you weight on earth.
Your mass and the mass of the moon set what you weigh on the moon. The
mass of the moon is much less than that of earth so you weight much
less on the moon.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Roger Halstead wrote in message . ..
On Sat, 27 Sep 2003 11:48:24 GMT, Dave Shrader
wrote:

I am 240 pounds 'mass' on earth. That's a fact.
No, in the US system of measurement your mass is measured in slugs.
your weigh is measured in pounds and is 240# on earth

In the metric system mass is in kg. Again the metric system is easier.
240#=109.091 kg

If you expect to sound like you have some expertise in this area, I
suggest you study up on precision, on significant digits and the like.

You can't start with a mass with only 2 or 3 at the most significant
digits, and get a conversion accurate to 6 significant digits.

Furthermore, if he were 240.000 lb, then he would be 108.862 kg, not
109.091 kg. You also cannot use a conversion factor with only 2 or 3
significant digits, and get a result with six significant digits (you
used 1 kg = 2.2 lb, whereas the actual definition of a pound is
exactly 0.45359237 kg).


I am 240 pounds 'mass' on moon. That's a weird assertion!

Your mass is still the same (109.091 kg), but your weight is
considerably less on the moon.

His mass is still the same, 240 lb, is every bit as true. What's this
bull**** about mixing together pounds and kilograms in a totally
confusing and stupid system of units? After all, your claim above was
that "in the US system of measurement your mass is measured in slugs"
so why aren't you using these units?

Yes, if his mass is 240 lb, you could also say that his mass is 7.5
slugs.

But by the same token, you could use one of the old non-SI metric
systems, and say that his mass is 11.1 hyls, in the system in which
the base units are the meter for length, the kilogram for force, and
the second for time.

But the existence of the hyl does not prove that kilograms are not
units of mass. By the same token, the existence of the slug does not
prove that pounds are not units of mass.

Each of those units, the slug and the hyl (aka the metric slug), exist
in only one particular subset of units, a subset which forms a
coherent system of units like SI, in which there is only one unit for
each different quantity and that unit is a unitary combination of the
base units.

The only system which uses slugs is normally identified as the English
(or British, this identifier being a matter of history and
derivation), or the U.S. (because it is also used here) "gravitational
foot-pound-second system of units." Your characterization of it as
"the U.S. system" is vague and misleading, overly broad. The only
system which has slugs excludes many of the units used in the United
States, such as pints and gallons and bushels and horsepower and Btu
and miles and ounces and psi.


If that assertion is true, who changed the density of the moon??

It has nothing to do with the assertion, but the mass of the moon is
less than the mass of the earth.

The mass of the Earth is in fact 81.3 times that of the earth's moon,
and you are right, it has absolutely nothing to do with what Dave
Shrader was talking about.

The mass of you and the earth sets what you weight on earth.
Your mass and the mass of the moon set what you weigh on the moon. The

No. Even accepting that you are using a force definition of the
ambiguous word weight (IOW, a definition nonstandard for the context
of body weight), there is one other factor that is also especially
important. After all, remember that I told you above that the mass of
the Earth is 81.3 times the mass of the moon. Do you think that the
force due to gravity that an object exerts on Earth will be 81.3 times
the force that the same object would exert on the moon? What do you
suppose that other important factor might be (hint--while the force
varies only linearly with mass, it varies in inverse proportion to the
square of this other factor).

mass of the moon is much less than that of earth so you weight much
less on the moon.

--
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
"It's not the things you don't know
what gets you into trouble.

"It's the things you do know
that just ain't so."
Will Rogers