Talk:Weight

This page is basically a long argument that the historically correct usage of weight is mass. But the origins of words do not determine their proper use, and anyways, weight was first coined back when people didn't have any concept of the distinction between mass and force due to gravity. I've removed the bit about scales, since it is the least sensical - scales measure force due to gravity in circumstances where it will ideally be proportional to mass, so to claim they are truly measures of one or the other seems kind of absurd. The rest could stand some editing, though. The distinction between pounds and pound-forces is not supported by older physics texts, which usually use pounds as forces and slugs for mass, while acknowledging a different system where pounds are masses and poundals are forces.

Admitedly the terminology for pounds is confusing, but you will find that the legal definition of pounds in the United States today is as a unit of mass.

A balance scale compares masses, it does not measure force due to gravity. You put the object to be weighed on one end of the balance. You then add weights of known mass on the other end of the balance, until the balance is level. This procedure requires acceleration due to gravity to work, but doesn't depend on the actual value of the acceleration. So it is a measure of mass, not force due to gravity. -- SJK

Disagree. You can use the exact same device to measure charges in an electromagnetic field, or the relative strengths of two springs. It's only measuring mass when you decide to interpret the results as mass; when you decide to interpret them as forces, it's measuring forces. It doesn't make any sense to talk about what a device is "truly" measuring when it's measuring two coincident things! I really think this article's emphasis on whether or not usages are correct, rather than what weight is, is a bad thing, and would vote for this passage to be removed and others to be rewritten, but I don't want to get into a back and forth edit war.

But when you use it to compare masses, the result does not depend on the force due to gravity. A scale balance will give you the same result on Earth as it will on Mars. A spring balance will not. -- SJK

However, scales depend on factors other than the masses and force due to gravity. When you try to use scales underwater, and the objects being weighed do not have the same density, you get incorrect measurements. Actually, this phenomenon (Archimedes' Force) occurs in any medium other than a vacuum, but it is almost negligible in air. In general, if you apply some vertical force on the masses, you mess up the scales' readings. What they really do is compare the forces acting on each side of the balance. Thus, I would not say that they measure mass. For something to measure a quantity, its output has to depend only on that quantity. For example, a barometer always measures air pressure; although it can be used to calculate elevation (if you know the relationship between elevation and air pressure) that is not what it actually measures. --KA

Minor correction: scales do not measure forces. If they did, the doctor's office couldn't weigh you with those small masses on the scales. Scales compare torques: when torques are imbalanced, the lever arm rotates, when the lever arm holds still the torques are the same (in opposite direction). Add a little geometry, and you can convert the torques to the net force directed radially. That is as much as you can say about a balance without adding other factors. If the forces are applied to the ends of strings attached to the lever arms of the balance (much the same way many balances have susbended trays on them) you can tell the direction of the force (a useful way to convert radial force to net force). To get to a measurement of mass takes: 1, a unidrectional field (maybe, this one could be corrected for with the strings, I'd have to think more to say for sure); 2, a uniform field (at least uniform enough that the geometry of the balance and/or the object does not effect the net force); 3, a field that is only proportional to the quantity you wish to measure.

BlackGriffen

Maybe this page explains what I was trying to get across better http://ourworld.compuserve.com/homepages/Gene_Nygaard/weight.htm

The comments still apply. Ancient peoples couldn't be talking about mass as opposed to gravitational force if they didn't have distinct concepts of each. Scales measure mass when you use masses for reference and forces when you use forces for references, and so to speak of them truly measuring one or the other is silly, modulo KA's comments above. And, btw, does anyone know if there is an official usage for the pound in Britain or elsewhere? America hardly determines universal standards for units, as the gallon proves.

The pound (technically, the pound advoirpois) is defined in the same way in both countries, since the 1950s, in terms of the kilogram. -- SJK

Ok. Well, one still finds a considerable body of literature using pounds exclusively as a unit of force, especially in derivative units (e.g. 550 foot-pounds/second = 1 horsepower), and it would be somewhat hypocritical to talk about historical usage and then turn around and label these as simple obsoletes. I think that, when usage is varied, an article should reflect varied usage and not try and impose a false order on reality.

An example of a case where common usage refers to force, and not mass, is when people say objects in space are weightless.

I'm not saying that weight cannot mean force, just that it is historically mistaken to claim that it should only mean force, or that people who say that "I weigh 50kg" are somehow being inaccurate.

Also, yes people in past centuries weren't entirely clear on the difference between mass and force due to gravity, but most of the time it was mass, not force due to gravity they were worrying about. If you weigh out 5 troy ounces of gold, do you want 5 ounces mass or 5 ounces force due to gravity? You are interested in the mass, not the force due to gravity. Similarly, if an apothecary weighed out 1 grain of some medicinal substance, they wanted 1 grain mass, not 1 grain force. Weighing is (and more importantly was) most commonly done to determine the amount of substance, not to determine how heavy it is. So even if they weren't entirely clear on the difference, they wanted mass. -- SJK

On Earth, weight refers to that quantity which is both mass and gravitational force because the two are identical there, and elsewhere the meaning is considerably clear. It doesn't matter which of mass and force people really wanted to be talking about back when they didn't distinguish the two, because they didn't distinguish the two. Nowadays the word tends to mean force when there is a difference, though it still is used to mean mass a lot of the time. Language changes. We want to reflect use, not what we believe use should be, or what we believe historical use better represented - actual historical use being of course both simultaneously.

The bit about scales I'd like to see removed, since as argued above it is incorrect, and the bit about weight historically meaning mass I'd like to see altered, since it is misleading at best. I'd also like to see the approach to legal resolutions straightened out, since we seem to accept the universality of the recommendation that pounds be mass but treat the recommendation that weight be force as a mere suggestion. If I change the article to take these into account, can I trust that you will not revert it, at least not without further discussion?

How about:

Weight, in physics the force that gravity exerts on a body. Compare mass.

What's all the fuss about? Sheesh. Ed Poor

At the very least, we should make clear that, historical usage aside, this encyclopedia uses the term weight to refer to force due to gravity. Otherwise, every link to this article will leave the reader confused: "Which meaning of weight are they currently using?" --AxelBoldt

I've finally done it, I've gone and blown it all up. Right now the article says that weight should mean force, at least in technical literature, which is possibly overkill but already present in the new introduction, and certainly in line with both what seems to be wikipedian consensus and the CPGM resolution. The stuff about weight historically meaning one or the other has been removed, since they were not distinguished and it is a bad idea to try and determine which people really meant, and the stuff about scales actually measuring one or the other has been removed, as the above comments (not all by me) provide ample justification for such a change, I'd say. I apologize for how radical this edit is and how completely it reverses the position, and would be more than happy for SJK or someone else to temper the article somewhat towards accepting mass as a valid alternate. I just don't think we should try and argue that it is somehow a better meaning.

(This means that most of this Talk page is now obsolete...)

Oops, I did it again (with apologies to B. Spears) I missed the SI thing at the bottom. So, let's discuss how to make the article serve all its purposes

distinguish between weight and mass, so we know which is which.
point out that they're still used interchangeably (at least by laymen)
give some sort of endorsement to the scientific usage.

I think the current article does just that, no? --AxelBoldt

When discussing scientific or engineering matters, I take pains to use force (measured in N-m or lb-ft) to mean force. But contemporary usage is fraught with references to 'weight' which "really" refer to mass. I used 'weights' on a balance scale to 'weigh' objects and determine their 'weight' (really mass, of course) in high school science classes.

N-m is work or energy, not force. --AxelBoldt

How weighty an issue is this, anyway (wink)?

Ed Poor

Too much jargon

Some people seem to have lost sight of the fact that this is an encyclopedic article, not merely a guide ot the interpretation of the jargon of particular petty priesthoods.

This is also a word is quite general use, and with quite specific meanings—meanings often at variance with the jargon of those priesthoods.

We would better serve our readers by making these distinctions clear. Enough of this burying your heads in the sand. Gene Nygaard 14:46, 17 Dec 2004 (UTC)

Scope of this article

In determining what should be included in this particular article "Weight" it is instructive to look at how the word is used on the pages on the "What links here" special page.

However, keep in mind that most of these are nothing more than brief mentions, not using any actual measurements of anything called weight.

Some might quibble with my characterization of almost every individual linking article, but if you want to comment on that it would be more helpful to discuss a broader class of them by the context in which "weight" is used in that group of articles.

Omitted are a redirect from Falling and five double-redirects under it.

I stubbed a new falling that includes a basic classical physics definition and some other lovely descent-related stuff. --Tony Sidaway|Talk 22:30, 2 Jan 2005 (UTC)

What links here? sorted by meaning

What links here? Sorted by units used for "weight"

This is the most instructive part—looking at how the word "weight" is used when it us used with actual measurements.

Note also that there are hundreds of other pages on Wikipedia which do measure other quantities identified by weight, but which do not link to this page. I'd bet that they are even more unbalanced towards the measurements of mass than this listing.

mass, uses kg, lb

Pound
Sputnik 1 -- uses kg, lb
Tupolev Tu-144 -- uses kg only
W. G. Grace -- uses kg, stone (no lb)
Weight training -- uses lb, kg
Sinker -- uses oz, lb
Commercial at -- defines at, arroba in terms of lb
Tael -- defines tael using oz troy and avdp, g
Crash test dummy -- uses kg, lbs
Canon de 65 M(montagne) modele 1906 -- uses kg only
Canon de 75 M(montagne) modele 1928 -- uses kg only
Oka -- just defines oka in kg
Avoirdupois -- just defines lb in grams, other units in lb
Tonnage -- just defines various tons in terms of kg or lb
Obolus -- just defines in terms of grams
Dick Tiger -- uses "pds"
BattleTech:Technology -- uses tons
W. G. Grace/temp -- uses stone only
oka (measure) -- just defines in kg
ThinkPad X40 -- uses kg, lb
CWT -- just defines in lb
Hundredweight -- defines in kg, lb
Little Britain -- uses stone
Ra's al Ghul -- uses kg, lb
Diving shot -- uses kg, lb
Trevalla -- uses kg only
Terex Titan -- uses tonnes only
LCM-8 -- uses tons (probably long tons) only
Units of measurement -- just defines lb in kg, kg in "weight" of liter
Aston Martin DB7 -- uses tonnes only
Tower pound -- just defines in grains
British 81 mm mortar -- uses kg only
Code Adam -- uses lb, kg
Tsukemono -- uses kg only
Displacement (fluid) -- uses long tons
RCMP recruiting -- uses kg, lb
User:Patrick/w -- uses kg
Ruby Lin -- uses kg, lb
14 (number) -- just definition of stone in lb

force, uses newtons, kgf, lbf

Specific impulse --uses N, and sort-of uses gf
Newton -- just defines, doesn't use, N
Talk:Newton (unit) -- just N, kgf definition
Normal force -- uses N
Animal locomotion on the surface layer -- uses dynes only

use no units for "weight"

I'll leave these jumbled together and unlinked.
Aircraft Aeronautics Aerodynamics Bone Balance Centripetal force Clinical depression Fetus Fall Gravity History of computing hardware Hail Mass Mineral Metallurgy Oscillation Scientific method SI derived unit Weightlessness Relative density Stone Gravitational constant Collision Amedeo Avogadro Clozapine Scale (measurement) Universal Product Code Valproic acid Gee Fundamental unit Timeline of gravitational physics and relativity Talk:Newton (disambiguation) Freefall Tandem bicycle Talk:Sputnik 1 Jam Power-to-weight ratio Connection Pound-force Heavy Haloperidol Fluphenazine Typical antipsychotic Risperidone Rechargeable battery Human physical appearance Unsprung weight Cephalic disorder Local food Buoyancy Talk:Mars Exploration Rover Mission Terminal velocity Thermostat Structural analysis Talk:Grain Unit of account Bulldozer Weight bearing Self image Wikipedia talk:WikiProject Space missions Bar (unit) Soap bubble Naruto geography User talk:80.255/archive 1 List of topics (scientific method) Boussinesq approximation List of physics topics R-Z Comptometer Hip dysplasia History of perpetual motion machines Cranial electrotherapy stimulation Magic School Bus episode guide Outrigger Blood donation Spotter Rolled Homogeneous Armour Devaluation Powered armor Talk:Crash test dummy Hydraulic accumulator Action stroke dance notation William Congreve (inventor) Monosoupape engine Deadbolt Wikipedia:Reference desk archive/June 2004 NLGI Grade List of -ight words Image:Aeroforces.jpg Allen Carr Talk:Relative density Wheelbase Talk:Internet Diplexer Weighing scale Apheresis User talk:GK Apparent weight Gravimetry Animal locomotion Tamp Wikipedia:Concise Decompression trapeze User:Anthony DiPierro/Everything else Haugh unit Burden

restoration

Body wt is a common (perhaps the most common) use of the word and predates the largely theoretical distinction between wt and mass. 99+% of our readers don't know the difference and should be at least educated, oriented, and sent to their topic of interest. I hope it doesn't pain you too much to retain the two small sections at the end even though I applaud your efforts at scientific rigor. alteripse 02:46, 5 Feb 2005 (UTC)

Latest edits by CYD

I'm glad to see that you are finally coming to your senses about this, CYD. Your last edit is much more reasonable than what you reverted to earlier. With a little more tweaking, it might even work.

However, your comment about "remove self-promotion link" is misplaced. That was here before I ever started editing Wikipedia (my first edit of any kind was 6 Dec 2004). You can see where it is mentioned in an unsigned comment here on this talk page; if you look in the history, you can see that it, and the link on the article page, were added more than three years earler, see talk page Revision as of 22:47, 2 Dec 2001 203.109.250.xxx . Though I wouldn't know how to do it myself, I have no doubt that somebody could track down that user as being someone other than me. Or maybe I did; some edits by 203.109.250.xxx are signed [[SJK]] and entries signed by SJK also appear on this talk page, and the comment about adding the link is worded as an extension of some of those comments.

Nonetheless, I don't think it would be appropriate for me to reinstate your deletion of the External link to my web page, though I have no objection if someone else choses to do so. Gene Nygaard 03:46, 5 Feb 2005 (UTC)

Who is more careful?

The statement that "In the physical sciences, people are usually more careful about the distinction between weight and mass" is a crock of nonsense.

First, it assumes facts not in evidence—that there is in fact always a "distinction between weight and mass". It is a logically flawed, circular argument to assume this as a fact in the first place, and then use it to prove the same point.

Second, the usage of the word "weight" is much more consistent and uniform in commerce than the usage of the word "weight" in the physical sciences.

Commerce usage:
- Weight is never a force when anybody talks about net weight of anything.
- You never hear of any government regulator mistakenly testing a scale used in commerce for its accuracy in measuring force rather than its accuracy in measuring mass. But then, they have a lot of shoulders to stand on; this was already old hat when Hammurabi included provisions regulating this weight in his Code of Laws some 3750 years ago.
- The troy units of weight, which are still used in commerce (even in the 21st century enjoying a special exception from the metrication laws of places such as Australia and the U.K., are always units of mass, never units of force. Those troy units were also the preferred units of Isaac Newton in the physical sciences (perhaps because he could borrow the scales of his employer at his day job as Master of the Mint), even though he liked the French toises, pieds, and pouces for length.
- Weight is never a force when anybody talks about carcass weight, even if they spell it carcase weight.
- Weight is never a force at the livestock auction markets in Saskatchewan, whether they are selling hogs in dollars per hundred kilograms or cattle in dollars per hundred pounds, which is no matter how you look at it a pretty weird way of doing things.
- Newtons are never legal units for the sale of goods by weight.
Physical sciences usage:
- Despite CYD's wishful thinking, the terms atomic weight, molecular weight, and formula weight are alive and thriving.
  - Just go look at a few of the zillions of Periodic Tables of Elements cluttering up the World Wide Web, and see how many of them use atomic weight (on many of them, you get details like this by clicking on the symbol for each element). Many of these are posted by educational institutions around the world.
  - Google—

            "molecular weight"                     3,250,000 hits
            "molecular weight" site:harvard.edu       12,600 hits
            "molecular weight" site:nist.gov           5,490 hits

- The rocket scientists at NASA tell us that the weight of the Apollo 11 Lunar Module at liftoff of its ascent stage was 10,776.6 lb.
- The thrust-to-weight ratio of that LM, in normal NASA usage of this term, was about 0.35 or less (they usually omit the units). Do the math. And the dimensional analysis.
- The verb to weigh is considered correct when used to mean "to measure the mass of" something, even when used by those who would not use the noun weight for the result of that weighing. Using to mass as a verb with this meaning is substandard usage which grates on the ears of most people, including many chemists and physicists.
- Physical scientists are often called on by their governments to help in the development of weapons of war. Go look into how the term throw weight is used. What are the proper SI units for this quantity? Hint: it is the same units used in various treaties.
- Then, of course, there is Henry Cavendish's paper, Weighing the Earth, a title never to be spoken aloud in an astronomy class.
Deceptiveness in the "physical sciences" classification:
- Those making this claim would like to have us believe that they are making broad generalizations about the entire scope of science and technology in general. So what we need as an aid to this discussion is the following glossary entry:
  - Physical sciences: a term referring the mechanics sections of introductory college physics textbooks published after 1980.
The physical sciences usage they'd like us to forget about:
- Engineering.
- The measurement of body weight by biologists, a measurement of mass. Same for paleontology as well.
- The measurement of human weight in the medical sciences, another measuremnt of mass.
- Drug dosages in milligrams per "kilogram of body weight" in veterinary science as well as in medical science.
- The use of "bushels by weight" and "finishing weight" of a hog in agricultural sciences.
- Archaeologists measuring the weight of bowls in grams.
- In aeronautics, the "empty weight" and "maximum takeoff weight" of an airplane.
- The term "dry weight" as it is used in various sciences. I've never seen a "dry weight" measured in newtons.
- The weight of a crash test dummy.

Then there's that heavy cream those physical scientists use in their coffee. No matter which definition of weight we use, a liter of heavy cream will weigh less than a liter of light cream! — Gene Nygaard 11:11, 5 Feb 2005 (UTC)

Retrieved from "https://academickids.com:443/encyclopedia/index.php/Talk:Weight"

Talk:Weight

Too much jargon

Scope of this article

What links here? sorted by meaning

means mass

means force due to gravity

means density

means an object

means both mass and force due to gravity, may be different people, esp. in talk

could mean either mass or force due to gravity, or meaning unclear

means force, but not due to gravity, or not just gravity

mathematics jargon meaning

do not use weight (other than link to here)

means none of the above

What links here? Sorted by units used for "weight"

mass, uses kg, lb

force, uses newtons, kgf, lbf

use no units for "weight"

restoration

Latest edits by CYD

Who is more careful?

Navigation

Search

Toolbox

Personal tools