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On Thu, 25 Sep 2003 01:16:33 GMT, Dave Shrader
wrote: Gene Nygaard wrote: [SNIP] Apparently you are claiming that pounds are not units of mass. Where did you learn that? Well, I learned that a Pound is a unit of Force. Well, I learned that a Slug [pound mass] is Pound*acceleration. Well, I learned that mass is pound*sec^2/foot. Where did I learn this? What's my source? Physics 101, University Physics, Sears and Zemansky, Addison-Wesley Publishing, 1956, Chapter 6, page 94. I hope tou don't need another reference? Now, what's your real problem? What are you trying to say? Can you quote it to me, specifically where it says that pounds are not units of mass? I'll bet you just misunderstood what it said. I have the 1970 edition of Sears and Zemansky myself, so I'm betting that if anything, what it actually says is clearer in that older edition than it is in the 1970 edition. Pounds force do exist, of course. What I'm asking you to show me is not that, but rather that pounds are not units of mass. Sears and Zemansky didn't lie about this in 1956. They might have been dishonest and deceptive about it, not concerned enough about the possibility that fools like you would misinterpret what they said or actually encouraging such misinterpretation. But they didn't lie about it. Some textbooks today might actually lie about it (or, alternatively, their authors are too poorly educated to know any better--take your choice). Gene Nygaard Dave, W1MCE Being the skeptic that I am, how can I convince myself that that is true? Is there some textbook, or something from some national standards agency, that would help me verify this? Gene Nygaard Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Wed, 24 Sep 2003 21:04:11 GMT, Richard Clark
wrote: On Wed, 24 Sep 2003 20:15:51 GMT, Gene Nygaard wrote: A balance, by implicit definition again, consists of comparing two masses under the influence of Gravity. Given it is a bridge, in a sense, the constant of Gravity is discarded from both sides and mass is compared only. It is a convenience of earthly expectations (and a defunct system of measurement) that the scale is marked in pounds. The matter of convenience is in the other direction, stupid; we're willing to substitute cheapness for accuracy in what we want to measure on those unreliable bathroom scales. They aren't any more accurate for measuring force than they are for measuring mass on Earth; haven't you ever weighed yourself on your mother's scale or somewhere else and found it differed from yours at home by several pounds? Do you automatically assume you've gained or lost that much weight. I've nowhere introduced the topic of accuracy. It has nothing to do with your original query. Weight and mass can both be measured to considerable accuracy. It all depends on method and standards. And mass can be measured with much more accuracy than force can, but that is entirely irrelevant to the point I was making. Your claim was that the mass-measuring balances are, for a matter of convenience, marked in units of force called pounds. I say that it is in fact the other way around, that the cheap force-measuring spring scales are marked in units of mass, which is indeed what we want to measure. The kilograms used throughout the world, including most hospitals in the U.S., for human body weight are indeed the proper SI units for this quantity. The pounds used for this purpose are the ones legally defined as 0.45359237 kg. Except, of course, for some science teachers and some physics books written recently by authors so miseducated (not uneducated, but actually mistaught) that they believe pounds are not units of mass. American Society for Testing and Materials, Standard for Metric Practice, E 380-79, ASTM 1979. 3.4.1.2 Considerable confusion exists in the use of the term weight as a quantity to mean either force or mass. In commercial and everyday use, the term weight nearly always means mass; thus, when one speaks of a person's weight, the quantity referred to is mass. . . . Because of the dual use of the term weight as a quantity, this term should be avoided in technical practice except under circumstances in which its meaning is completely clear. When the term is used, it is important to know whether mass or force is intended and to use SI units properly as described in 3.4.1.1, by using kilograms for mass or newtons for force. This ASTM E 380 and a separate ANSI/IEEE Standard have now been combined into a joint standard SI 10. I don't know if it says exactly the same thing; but I am certain it doesn't say anything directly contrary to this. Of course, NIST also tells us the same thing. I'll get to that below. A bathroom scale is not a balance. A balance has a scale (the marks along which the balance weights are moved and the markings upon those same weights). However, you do ask for a reference and acknowledge the NIST as a reputable source (many here ignore this commonplace): http://physics.nist.gov/PhysRefData/...constants.html There is absolutely nothing about pounds on this page. So don't be bull****ting us. That is the whole point. You don't see pounds there for mass do you? I don't see pounds as units of mass because this page just lists units in the International System of Units. Exactly. So why were you offering it as evidence that pounds are not units of mass? Do you think I'm that stupid, that you can pull the wool over my eyes so easily? Guess again. Show me something from NIST saying that pounds are not units of mass. Or from some textbook. That's because pounds are not a unit of mass. They are a unit of weight which is NOT a constant throughout the universe (nor on earth for that matter). Just your say-so? That's the best you can do? I am a trained Metrologist. I have measured mass traceable to the NIST. I have done this in four different Primary and Secondary Standards Labs. I was the head Metrologist of two of them. Wow! This is even better than I dreamed of. A genuine Capital-Letter Metrologist. Of course, it's also pretty sad, as most people will understand if they stick with me for the rest of this message. I'm sure that as a Metrologist, you are well aware of one particular subset of English units, used only in calculations, which is a coherent, gravitational foot-pound-second system in which the derived unit of mass is a slug, equal to 1 lbf·s²/ft. One of several such subsystems, of course. But if you are really a capital-letter Metrologist, and an old fart on top of it (that system with the slugs was never used in physics textbooks before 1940, and even a couple of decades later I learned the system I'm about to describe first, before learning the one with slugs--and you must be at least close to my age, and a genuine expert on weights and measures on top of it all), you'll have a damn hard time convincing me, or anyone else, that you are also not aware of a much older coherent foot-pound-second system of mechanical units, the absolute fps system in which the derived unit of force is the poundal, the force which will accelerate the base unit of mass in this system at a rate of one foot per second squared. Now, fill in the blank, please: The BASE UNIT OF MASS in this oldest English system of mechanical units is the _______________. Hint: it is the "p" in this fps system. BTW, while the gravitational fps system of units enjoyed a brief heyday in science in North America, outside of North America the absolute fps system with poundals remained the system of choice for doing calculations in English units. You probably also know that both of these limited use, coherent systems of units are, like SI, coherent systems of units. That means that in neither of these do we have any pints or gallons of any sort, not U.S. liquid, not U.S. dry, and not imperial. Nor are there any Btu, nor horsepower, in either system. Not only that, but there are no ounces (neither avoirdupois nor troy, nor U.S. nor imperial fluid ounces), no tons (neither long nor short, neither force nor mass), and no miles or inches (and thus no pounds force per square inch either). Of course none of our ordinary measurements are made in the context of any of these specialized systems of mechanical units which serve as calculation aids. The fact that many of the we use are not part of these systems is one bit of evidence of that fact. That fact that nobody ever measures (as opposed to calculating from other measurements) mass in slugs is another. The fact that we can generally choose any of several different systems of units to use in our calculations, with no change in difficulty, is still another piece in the puzzle. Let's look at what the English physicists William Thomson (for whom the SI unit of temperature is named) and Peter Guthrie Tate had to say about this way back in 1879, Treatise on natural philosophy, 1879, reprinted as Principles of mechanics and dynamics, quoted by Jim Carr in Apr 1998 on newsgroups alt.sci.physics, sci.engr, sci.physics. "By taking the gravity of a constant mass for the unit of force it makes the unit of force greater in high than in low latitudes. In reality, standards of weight are masses, not forces. They are employed primarily in commerce for the purpose of measuring out a definite quantity of matter; not an amount of matter which shall be attracted to the earth with a given force." ... description of merchant using spring scale to defraud or be defrauded depending on latitude, etc ... Jim Carr "It is therefore very much simpler and better to take the imperial pound ... as the unit of mass, and to derive from it, according to Newton's definition above, the unit of force." Then you might also know what "weights" means in the English versions of the international bodies charged with keeping our international standards: CGPM General Conference on Weights and Measures CIPM International Committee for Weights and Measures BIPM International Bureau of Weights and Measures In the introduction to their SI brochure (available at http://www.bipm.fr), the BIPM tells us for the first half-century of their existence, their only responsibility was keeping the standards for length and for mass. Take a wild guess which of those two corresponds to "weights" in these names. I can, OTOH, prove that pounds are indeed units of mass. By a reference found at the NIST? I think you would have done that by now if you could. Cocky little *******, aren't you! Just making clear that you accept the fact that doing so would prove you wrong, before I do it. I have already done so, of course, without referring to NIST, with that description of the absolute fps system above. But before we get to wandering around NIST's website, let's do a little primary source research, and find the definition which NIST considers controlling. For that we need to look to NIST's predecessor, the National Bureau of Standards, and to the law of the land. Earlier in the 20th century, Congress had had the sense to delegate the authority to make these definitions to the experts in the field who know what they are doing, and had given the predecessor of NBS this authority. This was officially implemented in 1959 by official regulatory action by NBS, made official with its publication in the Federal Register of 1 July 1959. This redefinition of the pound was done in accordance with an agreement reached among the national standards laboratories of several of the most advanced nations in the world, not back in the Dark Ages but in the middle of the 20th century, two years after Sputnik and the year before the International System of Units was introduced. The old U.S. definition, which had been a slightly different exact fraction of a kilogram for the 66 years before then, was replaced by the new international definition as 1 lb = 0.45359237 kg. You can read the current U.S. law (this Federal Register Notice), as well as a discussion of the earlier U.S. law and of the international agreement, at one of these web sites (same document both places): http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf http://gssp.wva.net/html.common/refine.pdf Of course, the same definition is was also adopted in Canada, in the U.K., in South Africa, in Australia, and in New Zealand, the other parties to this international agreement. It is also used all around the world, and was adopted by statute or regulation in some other countries not a party to the original agreement, such as Ireland. Now, let's get to the NIST web site. You obviously didn't follow the links you provided to get to the right place. Start with the one you recommended http://physics.nist.gov/cuu/Units/units.html click on Return to Units Home Page which takes you back up one level to http://physics.nist.gov/cuu/Units/index.html click on Bibliography: Online publications and citations to go to http://physics.nist.gov/cuu/Units/bibliography.html Go down to NIST Special Publication 811 and first of all, order yourself a free printed copy of this document. You need it. Then look at it in the online version, either in .html or in .pdf, whichever you prefer. I'll use the html version to give some links to specific parts of it below; I also have the printed version, and I have the .pdf version right on my computer. I already know what you think of NIST. In another message, you told us that "NIST describes all this at the links offered and they do not equivocate nor banter terms casually. For any Professional Engineer, they carry the force of law as the only authoritative source for definition. " This is NIST's official _Guide for the Use of the International System of Units (SI)_, by Dr. Barry N. Taylor, reviewed and approved by both the director of NIST and by his boss, the Secretary of Commerce. It is cited as an authority not only by many of the national standards agencies around the world, but also by the BIPM itself. First, a word about Dr. Barry N. Taylor. He is not only a professional metrologist with a Ph.D. in physics, but he has also served on both the Consultative Committe on Units which advises the CGPM (still on that, I think), and on the SUNAMCO Commission (Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants) of the International Union of Pure and Applied Physics (IUPAP). In other words, for the benefit of anyone else reading this, if Richard Clark is a "Metrologist" then Dr. Barry Taylor must be a "METROLOGIST" because even capitalizing all the letters won't adequately show the difference between the two, especially when it comes to expertise in the particular subfield related to teh definitions of units of measure. First, before we get to the pounds, let's digress a little bit and finish up that loose end I left above. http://physics.nist.gov/Pubs/SP811/sec08.html 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 same is true for pounds, of course. Units of mass in this context, as the term is used in physiology and medicine, and in sports--the reasons we normally weigh ourselves. There's more to the explanation in section 8.3, including a good discussion of the force definition of weight often used in physics and engineering. This section concludes with the excellent advice that whenever the word 'weight' is used, it should be made clear which meaning is intended. Now, let's go to the extensive list of conversion factors found in Appendix B to SP 811. http://physics.nist.gov/Pubs/SP811/appenB8.html#P To convert from to Multiply by pound (avoirdupois) (lb) 23 kilogram (kg) 4.535 924 E-01 pound (troy or apothecary) (lb) kilogram (kg) 3.732 417 E-01 [The 23 is a reference to a footnote in the printed and pdf versions, a note on a separate page in html] http://physics.nist.gov/Pubs/SP811/footnotes.html#f23 23 The exact conversion factor is 4.535 923 7 E-01. All units in Sec. B.8 and Sec. B.9 that contain the pound refer to the avoirdupois pound. This unit, of course, is not defined by this publication. This is just the legal definition made by NBS in 1959. Also, take a look at another section of American Society for Testing and Materials, Standard for Metric Practice, E 380-79, ASTM 1979. 3.4.1.4 The use of the same name for units of force and mass causes confusion. When the non-SI units are used, a distinction should be made between force and mass, for example, lbf to denote force in gravimetric engineering units and lb for mass. As you can see above, this sensible rule is also followed by NIST. It is also followed by NPL, the U.K. national standards laboratory. It is the older unit, the one more often used, and the one more likely to be used by those who care least about the distinction, which gets to use the original, unadorned symbol "lb"; it is the recent *******ization, the less often used unit, and the one more likely to be used by those who care most about the distinction, that must be distinguished by using a different symbol, "lbf" instead. That will prove that you are flat-out wrong in your claim that they are not. Well, I have seen a lot of math tossed over the transom here. But if we are to work by your own standard, cite an NIST reference. Just for practice, consider the troy system of weights. Unlike their avoirdupois cousins, and unlike grams and kilograms, the troy units of weight have never spawned units of force of the same name. They are always units of mass; a troy ounce is exactly 31.1034768 grams, by definition. There is not and never has been any troy pound force or troy ounce force. Hi Gene, Sounds like you proved a pound is not mass. No. You just proved that you are hopelessly ignorant when you get outside your fields and start discussing things such as linguistics, history, or the law. The pages I offered provide a meaningful quote: "The 3d CGPM (1901), in a declaration intended to end the ambiguity in popular usage concerning the word "weight," confirmed that: The kilogram is the unit of mass..." One of the most confusing and impossible to understand resolutions any political body has ever passed. You will note that NIST places no emphasis on this whatsoever. Yes, even then there were evidently enough scientists so utterly confused as to think that the standards they were keeping were standards of force rather than the standards of mass which they always had been. As were the old standards for pounds, naturally. Of course, by that time, we in the United States has already abandoned our independent standards for pounds, and we already defined them as an exact fraction of a kilogram. So where does that lead you? But of course, you are making a big mistake you think that this particular resolution meant that we couldn't use kilograms force. In fact, it was just the opposite--this very same resolution endorsed the use of grams force and kilograms force by adopting a standard acceleration of gravity, which is not a concept of physics but rather of metrology, something which serves no purpose other than defining units of force in terms of units of mass. Kilograms force had never been well-defined units before then. Neither had pounds force, of course--and what's more, even today pounds force don't have an official definition. The de facto standard, never officially adopted by any national or international standards agency, nor by any professional organization, is probably to use the same standard acceleration of gravity which is official for defining grams force and pounds force, namely 980.665 cm/s² in the units used in that 1901 resolution, before mks systems had come into use, at a time when neither slugs nor newtons had ever been used for the units they are now. Now go back to that Bibliography page on NIST and download NIST Special Publication 330, which includes the unofficial English version of this resolution, or at least the salient parts of it. http://physics.nist.gov/cuu/Units/bibliography.html Then pay special attention to the footnote added by NIST, found on page 17 in the document's own pagination (I don't know the page number in the pdf format): [dagger] USA Editor's note: In the USA, ambiguity exists in the use of the term weight as a quantity to mean either force or mass. In science and technology this declaration [CGPM (1901)] is usually followed, with the newton the SI unit of force and thus weight. In commercial and everyday use, weight is often used in the sense of mass for which the SI unit is the kilogram. Any other usage of "weight" in regard to the sensation of the action of Gravity upon an amount of mass is outdated by more than a century of understanding and convention. You said weight is a force. This resolution clearly said that weight is not a force, but merely something "in the nature of a force," whatever the hell that is supposed to mean. But fortunately, in any case, nobody was ever damn fool enough to give the 1901 CGPM any say-so on what "weight" means for the "net weight" of my bag of sugar, or for the troy weight of a bar of gold or platinum. That's outside their authority. That resolution isn't seriously offered as proof of any change in meaning of the word. In fact, I doubt that the 1901 CGPM ever intended to change the meaning of the word--they wrongly thought that they were merely stating existing definitions. "Outdated by more than a century of understanding and convention"? Nonsense. Go back and read that section 8.3 of NIST Special Publication 811 again. That's 1995--hardly a century ago. Need more. Here's 1989, in the still-effective official National Standard of Canada, CAN/CSA-Z234.1-89 Canadian Metric Practice Guide: 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. Note that "nearly always" is much stronger than "primarily"; they even got that part right. Note further the difference usage for the noun forms in 5.7.3 and the verb forms in 5.7.4; for the former, the meaning is context-specific, but for the latter that definition is unqualifiedly called "correct" (which does not, of course, say anything one way or the other about the use of the verb to mean to determine the force due to gravity, which is also correct). Need more. Here's 2003, on the web pages on the National Physical Laboratory (NPL), the official national standards agency of the United Kingdom of Great Britain and Northern Ireland: NPL FAQ 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 that they are talking about DIFFERENT MEANINGS of the word "weight." Just as NIST does. Just as ASTM does. Just as the Canadian Standard for Metric Practice does. Just as any good dictionary does. That, of course, is how the word weight entered the English language over 1000 years ago, meaning the quantity measured with a balance. A quantity which you yourself explained so lucidly to be mass, not the force due to gravity. Of course, when those tribesmen in what is now England were looking for a word to use to measure how much stuff they have, when they buy and sell goods, they didn't make any mistake when they invented this word "weight" for that purpose, did they? They couldn't have used "mass" for this quantity instead, unless they had happened to choose those phonemes for the word they invented. Mass didn't have this meaning until more than 750 years later, when some obscure translator translated Newton's major work into English after Newton's death. Or do you think it was a mistake that these heathens didn't figure out the God-given word they were supposed to invent for this purpose? There is no error when we use the very same word, with the very same meaning, for the very same purposes today. We have a prior claim to this word by 3/4 of a millennium over the physicists who recently borrowed it and often use it with a somewhat different meaning. Sometimes we borrow the physicists meaning, sometimes we use the original meaning. But like all the experts tell you, because of these ambiguities, you should just avoid using the term "weight" in a technical context--and if you do use it, make damn sure your meaning is clear. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ Gentlemen of the jury, Chicolini here may look like an idiot, and sound like an idiot, but don't let that fool you: He really is an idiot. Groucho Marx |
On Thu, 25 Sep 2003 03:41:10 GMT, Gene Nygaard
wrote: Do you think I'm that stupid, that you can pull the wool over my eyes so easily? Hi Gene, As I pointed out earlier, your feelings belong at the end of the line with the rest whose minds I cannot change. 73's Richard Clark, KB7QHC |
Gene Nygaard wrote:
Apparently you are claiming that pounds are not units of mass. Where did you learn that? Being the skeptic that I am, how can I convince myself that that is true? Is there some textbook, or something from some national standards agency, that would help me verify this? Gene Nygaard Nice web page you have on the subject, but I suspect it is not quite so cut and dried as you make out. I have a strong recollection (from many years ago) of being taught that pounds where force. Going to google with 'pound mass force' yields some modern university teaching material which says the same. My ancient thermo text uses lbf and lbm throughout to eliminate confusion. There seems to be little doubt that today the pound is defined in terms of the kilogram so is clearly a unit of mass. But usage of the pound seems to be less consistent. Consider pounds per square inch or foot-pounds; in each of these the pound is a unit of force. I expect the definition of pound will be argued for some years to come. Let's just all go metric. The only really confusing measure there seems to be the definition of the litre. ....Keith |
Gene, thanks for the compliment in calling the Program Chief Engineer
of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool. It says a lot about you. I forgive you. Dave, W1MCE + + + Gene Nygaard wrote: not concerned enough about the possibility that fools like you |
On Thu, 25 Sep 2003 12:13:47 GMT, Dave Shrader
wrote: Gene, thanks for the compliment in calling the Program Chief Engineer of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool. It says a lot about you. I forgive you. Gee, if I'd known you were so important, I'd really have taken you to task for being too damn stupid to understand what you read in Sears and Zemansky! Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Thu, 25 Sep 2003 12:13:47 GMT, Dave Shrader
wrote: Gene, thanks for the compliment in calling the Program Chief Engineer of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool. It says a lot about you. I forgive you. Dave, W1MCE + + + Gene Nygaard wrote: not concerned enough about the possibility that fools like you Since you aren't honest enough to tell us exactly what Sears and Zemansky said in 1956, I'll tell everyone what they said in 1970. If there are any significant differences, feel free to point them out. This thing is, I know that Sears and Zemansky weren't going to lie about this, because they grew up using poundals, which are by definition the force which will accelerate a MASS of 1 lb at a rate of 1 ft/s². Francis Weston Sears and Mark W. Zemansky, University Physics, Addison-Wesley, 4th ed., 1970. [page 3] 1 pound mass = 1 lbm = 0.45359237 kg [The actual number will, of course, be different in 1956, because the U.S. didn't adopt this definition until 1959 (it had been in use in Canada since 1953, six years before the international redefinition).--GAN] [page 4] We select as a standard body the standard pound, defined in section 1-2 as a certain fraction (approximately 0.454) of a standard kilogram. [page 59] In setting up the mks and cgs systems, we first selected units of mass and acceleration, and defined the unit of force in terms of these. In the British engineering system, we first select a unit of force (1 lb) and a unit of acceleration (1 ft s^-2) and then define the unit of mass as the mass of a body whose acceleration is 1 ft s^-2 when the resultant force on the body is 1 lb. end quote Now, Sears and Zemansky might be incompetent for not allowing for the fact that there are going to be people out there who are too blamed stupid to understand that that adjectival phrase "British engineering" has some meaning, and that it identifies one particular limited subset of the British units. It's perhaps even understandable, because that fact would be quite clear to anyone who, like them, had grown up using poundals in a "British absolute" system of units. However, that doesn't change the fact that you are in fact one of the people who are that stupid. -- 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 |
On Thu, 25 Sep 2003 12:13:47 GMT, Dave Shrader
wrote: Gene, thanks for the compliment in calling the Program Chief Engineer of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool. Is that as good as being chief of the Mars Climate Orbiter program as evidence of competence in the use of units of measure? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
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On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark
wrote: On Thu, 25 Sep 2003 06:45:29 -0400, wrote: Let's just all go metric. The only really confusing measure there seems to be the definition of the litre. ...Keith Hi Keith, You mean liter? ;-) Up there in the Great White North, they use those dinky little "litres" where it takes 4.54609 of them to make a gallon, rather than the man-sized liters we have, which only take 3.785411784 to make a gallon. ;-) Unless, of course, you are talking about blueberries, where we use an inbetween liter where it takes 4.40488377086 liters to make a gallon (which we actually don't use much under that name any more, though we do still use its quart and pint subdivisions). Gene Nygaard |
"Fundamentals of Physics", Haliday and Resnick, Second Edition, 1981
Appendix F, Conversion Factors Mass "Quantities in the colored areas [ounce, pound, ton] are not mass units but are often used as such. When we write, for example 1 kg "=" 2.205 lb this means that a kilogram is a _mass_ that _weighs_ 2.205 pounds under standard condition of gravity (g = 9.80665 m/s^2)." The units dyne, Newton, pound, and poundal are listed elsewhere in Appendix F as units of force. 73, AC6XG Gene Nygaard wrote: On Thu, 25 Sep 2003 12:13:47 GMT, Dave Shrader wrote: Gene, thanks for the compliment in calling the Program Chief Engineer of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool. It says a lot about you. I forgive you. Dave, W1MCE + + + Gene Nygaard wrote: not concerned enough about the possibility that fools like you Since you aren't honest enough to tell us exactly what Sears and Zemansky said in 1956, I'll tell everyone what they said in 1970. If there are any significant differences, feel free to point them out. This thing is, I know that Sears and Zemansky weren't going to lie about this, because they grew up using poundals, which are by definition the force which will accelerate a MASS of 1 lb at a rate of 1 ft/s². Francis Weston Sears and Mark W. Zemansky, University Physics, Addison-Wesley, 4th ed., 1970. [page 3] 1 pound mass = 1 lbm = 0.45359237 kg [The actual number will, of course, be different in 1956, because the U.S. didn't adopt this definition until 1959 (it had been in use in Canada since 1953, six years before the international redefinition).--GAN] [page 4] We select as a standard body the standard pound, defined in section 1-2 as a certain fraction (approximately 0.454) of a standard kilogram. [page 59] In setting up the mks and cgs systems, we first selected units of mass and acceleration, and defined the unit of force in terms of these. In the British engineering system, we first select a unit of force (1 lb) and a unit of acceleration (1 ft s^-2) and then define the unit of mass as the mass of a body whose acceleration is 1 ft s^-2 when the resultant force on the body is 1 lb. end quote Now, Sears and Zemansky might be incompetent for not allowing for the fact that there are going to be people out there who are too blamed stupid to understand that that adjectival phrase "British engineering" has some meaning, and that it identifies one particular limited subset of the British units. It's perhaps even understandable, because that fact would be quite clear to anyone who, like them, had grown up using poundals in a "British absolute" system of units. However, that doesn't change the fact that you are in fact one of the people who are that stupid. -- 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 |
Gene Nygaard wrote: Up there in the Great White North, they use those dinky little "litres" where it takes 4.54609 of them to make a gallon, rather than the man-sized liters we have, which only take 3.785411784 to make a gallon. ;-) I suspect it's not the litre which is different, but the gallon which is different. The British Imperial Gallon occupies 277.4 in^3, while the gallon you're thinking of occupies 231 in^3. What's your opinion of converting US speedometers from miles/hr to furlongs/fortnight? 73, AC6XG |
Jim Kelley wrote:
"Quantities in the colored areas [ounce, pound, ton] are not mass units but are often used as such. What is the mass of a banana slug in slugs? -- 73, Cecil, W5DXP |
Cecil Moore wrote: Jim Kelley wrote: "Quantities in the colored areas [ounce, pound, ton] are not mass units but are often used as such. What is the mass of a banana slug in slugs? Ask somebody at UC Santa Cruz. ;-) 73, ac6xg |
You are equating pound and POUNDAL ['pound mass']. They are two
different things. ---------------------------------------- Sears and Zemansky, 1956, Table 5-1, page 77 Systems of units Force Mass Acceleration Engineering pound Slug ft/sec^2 mks newton kilogram m/sec^2 cgs dyne gram cm/sec^2 ---------------------------------------- "One standard pound, by definition, is a body of mass 0.4535924277 kg." "Since the weight of a body is a force, it must be expressed in units of force. Thus in the engineering system weight is expressed in POUNDS; in the mks system, in Newtons; and in the cgs system, in dynes." Unless you disagree with Newton's Second Law, F=ma, Force [pounds] and mass [slugs] are related by acceleration [of gravity, for example]. So, my weight [240 pounds] = my mass [7.45 slugs]*[gravity of 32.2 ft/sec^2]. ----------------------------------------- If you want to argue, go ahead. I cited a source as you asked. Now you choose to disagree with that source. My final comment: Does a newton[force] = a kilogram[mass]?? -------------- Conclusion: Force = pounds, or newtons, or dynes. Mass = Slug, or kilogram, or gram Acceleration = ft/sec^2, or m/sec^2, or cm/sec^2 ---------------------------------------- Don't be so everbearing! It does not become you or enhance you statements. |
Gene Nygaard wrote:
On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark wrote: On Thu, 25 Sep 2003 06:45:29 -0400, wrote: Let's just all go metric. The only really confusing measure there seems to be the definition of the litre. ...Keith Hi Keith, You mean liter? ;-) It has to be litre so that it can rhyme with metre. Up there in the Great White North, they use those dinky little "litres" where it takes 4.54609 of them to make a gallon, rather than the man-sized liters we have, which only take 3.785411784 to make a gallon. ;-) Unless, of course, you are talking about blueberries, where we use an inbetween liter where it takes 4.40488377086 liters to make a gallon (which we actually don't use much under that name any more, though we do still use its quart and pint subdivisions). We also have the Texas sized foot of 12.789 inches (legal for surveying only in Quebec, they say). But it seems that in the great country to the south there are also two definitions for the foot: 0.3048 meter and 1200/3937 meter. When I buy a tape measure made in the U.S.A. am I getting long feet or short feet? ....Keith |
On Thu, 25 Sep 2003 19:11:42 -0400, wrote:
Gene Nygaard wrote: On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark wrote: On Thu, 25 Sep 2003 06:45:29 -0400, wrote: Let's just all go metric. The only really confusing measure there seems to be the definition of the litre. ...Keith Hi Keith, You mean liter? ;-) It has to be litre so that it can rhyme with metre. Up there in the Great White North, they use those dinky little "litres" where it takes 4.54609 of them to make a gallon, rather than the man-sized liters we have, which only take 3.785411784 to make a gallon. ;-) Unless, of course, you are talking about blueberries, where we use an inbetween liter where it takes 4.40488377086 liters to make a gallon (which we actually don't use much under that name any more, though we do still use its quart and pint subdivisions). We also have the Texas sized foot of 12.789 inches (legal for surveying only in Quebec, they say). Interestingly enough, Thomas Jefferson used Isaac Newton's measurements of the length of a seconds pendulum at various latitudes in terms of these feet, the royal foot of Paris, to calculate how long his foot would be in terms of the English feet then in use, when he proposed a decimal system based on the foot in 1790, before the metric system had been invented. In Jefferson's system, a metre would have been a cubic inch (0.001 cubic foot), and a metre of cool water would have a mass of 1 ounce (0.1 pound), and an ounce of 11/12 silver would have been a dollar. Plan for establishing uniformity in the Coinage, Weights, and Measures of the United States. http://ourworld.compuserve.com/homep...jeff.htm#from2 Some surveys in the United States (Lousiana) were originally done in these feet also, with lengths and areas in arpents. Some land grants in southwestern states were in terms of varas of various sizes, with areas expressed in labors and leagues. But it seems that in the great country to the south there are also two definitions for the foot: 0.3048 meter and 1200/3937 meter. When I buy a tape measure made in the U.S.A. am I getting long feet or short feet? The short ones, of course. The same document I cited before, the Federal Register notice which is the U.S. law redefining the yard as 0.9144 m and the pound as 0.45359237 kg spells out the limited surveying purposes for which the old definition would continue to be used. http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf http://gssp.wva.net/html.common/refine.pdf Seriously, you are buying a lot better quality tape measures than I have ever used, if you expect them to be accurate to that 2 parts per million difference. Are any tape measures that good? You will, of course, have to be making temperature corrections as well. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Thu, 25 Sep 2003 11:51:47 -0700, Jim Kelley
wrote: "Fundamentals of Physics", Haliday and Resnick, Second Edition, 1981 Appendix F, Conversion Factors Mass "Quantities in the colored areas [ounce, pound, ton] are not mass units but are often used as such. When we write, for example 1 kg "=" 2.205 lb this means that a kilogram is a _mass_ that _weighs_ 2.205 pounds under standard condition of gravity (g = 9.80665 m/s^2)." The units dyne, Newton, pound, and poundal are listed elsewhere in Appendix F as units of force. 73, AC6XG Apparently Halliday and Resnick were a lot smarter a couple of decades earlier, when they were only a little past their prime: Robert Resnick and David Halliday, Physics For Students of Science and Engineering, John Wiley & Sons, 1960. [page 10] Legally, the pound is a unit of mass. But in engineering practice the pound is treated as a unit of force or weight. This has given rise to the terms pound-mass and pound- force. The pound mass is a body of mass 0.45359237 kg; no standard block of metal is preserved as the pound- mass, but like the yard it is defined in terms of the mks standard. The pound-force is the force that gives a standard pound an acceleration equal to the standard acceleration of gravity, 32.1740 ft/sec². So what are you going to believe? The main text of a book which actually uses pounds? Or something hidden away in an appendix (which the authors likely assinged some secretary to put together for them), in a book which doesn't even use pounds? Now go back in the book you have, and take a look at some of the earlier stuff in it. [page 356] In the engineering system the unit of heat is the British thermal unit (Btu), which is defined as the heat necessary to raise the temperature of one pound of water from 63 to 64°F. How much water? You don't think that this is the amount of water that exerts a certain amount of force due to gravity, do you? What about when they give specific heat capacity in units expressed in as Btu/lb °F in this book? What the hell do you suppose those units in the denominator are? The corresponding metric unit in their book are "cal/g°C"; does that give you any clues? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Thu, 25 Sep 2003 20:06:37 GMT, Dave Shrader
wrote: You are equating pound and POUNDAL ['pound mass']. They are two different things. Good grief! Go find a dictionary, or a physics book published before 1940 (and a number of them published later as well, it's just that for the 60 years before then it's a virtual certaintly that you'll see poundals used in these textbooks). Poundals are unit of force. Not units of mass. A poundal is not a pound mass; it is not mass at all. A poundal is also not a pound force. In fact, it takes 32.16 pdl or 32.1740... pdl or 32.175 pdl, or something in that neighborhood, to make a pound force. The exact number will depend on how you choose to define a pound force, which doesn't even have an official definition. The de facto standard today is to define it so that it has the same relationship to a pound as a kilogram force has to a kilogram. Or, that a pound force has the same relationship to a kilogram force as a pound has to a kilogram. That's what I'll use for any other related numbers below. ---------------------------------------- Sears and Zemansky, 1956, Table 5-1, page 77 Systems of units Force Mass Acceleration Engineering pound Slug ft/sec^2 mks newton kilogram m/sec^2 cgs dyne gram cm/sec^2 ---------------------------------------- Still too ****ing dumb to see any adjective there, identifying a particular subset of English units? Even after it has been specifically pointed out to you? You know, I was tempted to give you the benefit of the doubt, and assume that this had been sent before you had a chance to read my discussion of the 1970 edition of Sears and Zemansky. But then I double checked, not only that it graphically appeared to below that message on my newsreader, but also that your message did indeed in References the message ID of that one in which I discussed the 1970 ecition. "One standard pound, by definition, is a body of mass 0.4535924277 kg." I told you the number would be different, didn't I--but that S&Z would not lie to you about the fact that pounds are units of mass. "Since the weight of a body is a force, it must be expressed in units of force. Thus in the engineering system weight is expressed in POUNDS; in the mks system, in Newtons; and in the cgs system, in dynes." Do you see any adjective modifying "system" here, in each of the three times it is used? Does the existence of a kilogram force prove that kilograms are not units of mass? No. Does the existence of a pound force prove that pounds are not units of mass? No. Do you know that what they call the "engineering" system is, like SI, a coherent system of units, as that term is used in the jargon of metrology? Do you know what that means? It means that there is only one unit for each different quantity, and that that unit is a unitary combination of the base units. Do you know the implications of that? That means that this system which they identify as the "engineering system" doesn't have any pints or gallons, no Btu or horsepower, no ounces or inches or miles or furlongs or fortnights. That's the only system that includes slugs--the one that doesn't have a whole lot of our commonly used units. What's more, that's only one of several such systems. Some of the others include the absolute fps system (the one with pounds for mass and poundals for force), the gravitational inch-pound-second system (no slugs here either; the unit of mass in this system, equal to 1 lbf·s²/in, or about the weight (a synonym for mass in this case, of course) of the heaviest NFL linemen today, is probably most often used without a name, though some NASA engineers have called it a "slinch"). Unless you disagree with Newton's Second Law, F=ma, Force [pounds] and mass [slugs] are related by acceleration [of gravity, for example]. You can just as easily say that force [poundals] and mass [pounds] are related by the acceleration [ft/s²]. It's every bit as true--and that system has been around a lot longer than the one with slugs. Furthermore, Newton didn't use symbol to express this, and he only said that force is proportional to mass times the acceleration of gravity. Symbolically, that's F = kma. Using this more general form, you can use any units you want to for each of these quantities, as long as you make the constant k fit with them. That's what must be done in the system generally called the English "engineering" system of units (Sears and Zemansky are idiots who aren't even able to understand the distinction between the system identified by this term in normal usage by most other people, and the one they call by this name which everyone else calls the "gravitational" or "gravimetric" fps system of units). In what everyone else calls the engineering system of units, pounds are used for mass and pounds force for force, and for Newton's Second Law we have F = kma where k = 0.03108095 = 1/32.1740. So, my weight [240 pounds] = my mass [7.45 slugs]*[gravity of 32.2 ft/sec^2]. ----------------------------------------- If you want to argue, go ahead. I cited a source as you asked. Now you choose to disagree with that source. Go read my quotes from NIST and from ASTM on the subject of human body weight in my longest reply to Richard Clark. My final comment: Does a newton[force] = a kilogram[mass]?? No. The numbers won't even be the same, unless you happen to be some place outside this world where the local acceleration of free fall is pretty close to 1 m/s². Furthermore, a kilogram force doesn't equal a kilogram either, not even if you call it by its other name, the kilopond. They measure different quantities. On earth, the numbers associated with each might be close to each other if the force you are measuring is the force due to gravity--but that doesn't make them "equal." Now here's something else for you to chew on. Just to show that there have been people using metric units who have been bound and determined to show that they can be every bit as silly as those using English units, look up a unit of mass known variously as the hyl, or by the German acronym TME, or as the mug, which is derived from another of its names, the "metric slug." This is the mass which a kilogram of force will accelerate at a rate of 1 m/s². In that system, the base units are the meter for length, the second for time, and the kilogram for force, with the hyl as the coherent, derived unit of mass. Note that in that system, kilograms are never units of mass. Exactly the same as that system which Sears and Zemansky mislabel the "engineering" system, a similar limited subset of the English units rather than of the metric units, in which subset the pound is not used as a unit of mass. Granted, that system probably never did see extensive use, and I haven't seen it used at all recently. But it's mere existence shoots all kinds of holes in your theories related to Newton's second law, and all the different names that the mass unit in this system has been given are clear evidence that it has been independently reinvented many times over. The existence of the hyl does not prove that kilograms are not units of mass. The existence of the slug does not prove that pounds are not units of mass. -------------- Conclusion: Force = pounds, or newtons, or dynes. Mass = Slug, or kilogram, or gram Acceleration = ft/sec^2, or m/sec^2, or cm/sec^2 ---------------------------------------- Don't be so everbearing! It does not become you or enhance you statements. It's a tradeoff I'm willing to accept as the price of getting the message through some awfully thick skulls. After all, there are a lot of dearly held memories of favorite teachers out there, and it's awfully hard for anyone to admit that some favorite might actually have led them astray. For example, what about all those pounds you see in the grocery store? You've been ignoring them for a long time, haven't you? Or are you really so god-awful stupid as to think that when we buy and sell goods by "weight" we'd want to measure some quantity that varies with location? PHASE II Now, let's move on to Phase II of our examination of Sears and Zemansky. Once again, I'll use the 1970 edition. Feel free to jump in as show us that they said essentially the same thing in 1956. Francis Weston Sears and Mark W. Zemansky, University Physics, Addison-Wesley, 4th ed., 1970. [page 228 (formula changed to one line)]: If the system undergoes a temperature change dt, the specific heat capacity c of the system is defined as the ratio of the heat dQ to the product of the mass m and temperature change dt; thus c = dQ/(m dt) The specific heat capacity of water can be taken to be 1 cal g-1 (C°)-1 or 1 Btu lb-1 (F°)-1 for most practical purposes. Tell me, what exactly does "lb" mean in this quote? Hints: 1. Look at what they tell you the denominator is in words. That would the first quantity identified as part of the "product." 2. Look at the unit in the same position as "lb" in the calories formula. [page 230] Mechanical engineers frequently use the British thermal unit (Btu), defined as the quantity of heat required to raise the temperature of 1 lb (mass) of water from 63°F to 64°F. The following relations hold: 1 Btu = 778.3 ft lb = 252.0 cal = 1055 J. How much water? [page 232] The quantity of heat per unit mass that must be supplied to a material at its melting point to convert it completely to a liquid at the same temperature is called the heat of fusion of the material. The quantity of heat per unit mass that must be supplied to a material at its boiling point to convert it completely to a gas a the same temperature is called the heat of vaporization of the material. Heats of fusion and vaporization are expressed in calories per gram, or Btu per pound. Thus the heat of fusion of ice is about 80 cal g^-1 or 144 Btu lb^-1. The heat of vaporization of water (at 100°C) is 539 cal g^-1 or 970 Btu lb^-1. Some heats of fusion and vaporization are listed in Table 16-2. Now, it doesn't take a whole lot of genius to figure out what the quantities are which are measured in those units with the -1 exponents, does it? But you don't even have to guess. Sears and Zemansky come right out and tell you. For you and some of the other slow-witted folks in this thread, here's a hint: Look for the seventh word in each of the first two sentences, that little word sandwiched in between the words "unit" and "that." Did you find it? Do you notice anything strange here? Something different from that textbook which Keith described for us, which used "lbm" for pounds mass and "lbf" for pounds force? Sears and Zemansky, earlier in the book, use the word "pound" and the symbol "lb" for units of force. But here they are using the word "pound" and the symbol "lb" for units of mass. I feel sorry for you if you had to learn physics from idiots like this. But that still doesn't excuse your ignorance half a century later; you've had lots of opportunities in the intervening years to figure out the truth on your own. Gene Nygaard Time flies like an arrow; fruit flies like a banana. |
Wow!
In SI: force is in Newtons mass is in kg distance is in meters time is in seconds - and answers are always in SI units if you use SI units. A mass in a gravitational field has a force associated. That force is not a mass even if it is (some of the time) proportional to mass. When certain kinds of engineers provide me with specifications involving pounds I shudder. Each use is converted into its equivalent in SI. The context helps. An assumption of the strength of the gravitational field needs to be used. Then I evaluate their work using SI (and the same assumption about the gravitational field). In SI, force and mass are quite distinct. I continue to be amazed by the awesome ability of some engineers to use a single term for two entirely different things. Use SI and the answers are SI. 73 Mac N8TT -- J. Mc Laughlin - Michigan USA Home: |
"J. McLaughlin" wrote:
When certain kinds of engineers provide me with specifications involving pounds I shudder. Each use is converted into its equivalent in SI. The context helps. An assumption of the strength of the gravitational field needs to be used. Then I evaluate their work using SI (and the same assumption about the gravitational field). In SI, force and mass are quite distinct. I continue to be amazed by the awesome ability of some engineers to use a single term for two entirely different things. Use SI and the answers are SI. This captures the essence of the issue. The question is not so much 'are pounds mass or force?', but, rather, 'what did the author mean when writing pounds?' An engineer who believes that pounds are always mass will make just as many errors as one who believes pounds are always force. ....Keith |
On Thu, 25 Sep 2003 12:02:12 -0700, Jim Kelley
wrote: Gene Nygaard wrote: Up there in the Great White North, they use those dinky little "litres" where it takes 4.54609 of them to make a gallon, rather than the man-sized liters we have, which only take 3.785411784 to make a gallon. ;-) I suspect it's not the litre which is different, but the gallon which is different. The British Imperial Gallon occupies 277.4 in^3, while the gallon you're thinking of occupies 231 in^3. Oh, good grief. Don't tell me the Canucks use different cubic inches too, and don't even distinguish them with the spelling like they do for "litres" vs. "liters"! Are you ready for your next assignment, Sherlock? I'm wondering if you'd be willing to take on another job for me. Do you suppose you could help me track down a missing wink? Apparently there was one that didn't show up on your newsreader--they look something like this-- ;-) What's your opinion of converting US speedometers from miles/hr to furlongs/fortnight? I think you'd be one of those guys who try to talk the talk, without having learned how to walk the walk. You've never actually calculated any speeds in furlongs per fortnight yourself, have you? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Thu, 25 Sep 2003 23:28:25 -0400, "J. McLaughlin"
wrote: Wow! In SI: force is in Newtons mass is in kg distance is in meters time is in seconds - and answers are always in SI units if you use SI units. A mass in a gravitational field has a force associated. That force is not a mass even if it is (some of the time) proportional to mass. When certain kinds of engineers provide me with specifications involving pounds I shudder. Each use is converted into its equivalent in SI. The context helps. An assumption of the strength of the gravitational field needs to be used. Then I evaluate their work using SI (and the same assumption about the gravitational field). In SI, force and mass are quite distinct. I continue to be amazed by the awesome ability of some engineers to use a single term for two entirely different things. It helps to be too stupid to know that there are in fact two entirely different things. There are several of those people in this thread. Not for the accuracy of the result, of course. But you can blithely plug in the numbers and get an answer of some sort. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
"Gene Nygaard" wrote in message ... Are you ready for your next assignment, Sherlock? I'm wondering if you'd be willing to take on another job for me. Do you suppose you could help me track down a missing wink? Apparently there was one that didn't show up on your newsreader--they look something like this-- ;-) Well, Gene. One never knows. I appologize. Your bit about the pound was funny too, but didn't have the smiley face. Next you'll be telling us it's a unit of currency! :-) What's your opinion of converting US speedometers from miles/hr to furlongs/fortnight? I think you'd be one of those guys who try to talk the talk, without having learned how to walk the walk. You've never actually calculated any speeds in furlongs per fortnight yourself, have you? A grad student an I made an overlay for his speedometer - must have been close to 15 years ago now. 73, Jim AC6XG |
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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 Thu, 25 Sep 2003 07:14:09 GMT, Richard Clark
wrote: On Thu, 25 Sep 2003 03:41:10 GMT, Gene Nygaard wrote: Do you think I'm that stupid, that you can pull the wool over my eyes so easily? Hi Gene, As I pointed out earlier, your feelings belong at the end of the line with the rest whose minds I cannot change. I proved you wrong, from the NIST site--your groundrules--and from many other sources as well. I gave you a web page from NIST defining the pound as a unit of mass exactly equal to 0.45359237 kg. Now I have a challenge for you, Mr. 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. Are you up to the challenge? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Fri, 26 Sep 2003 18:21:49 GMT, Gene Nygaard
wrote: Now I have a challenge for you, Mr. Metrologist: Hi Gene, What are your credentials? Can one expect you have at least a degree in English? ;-) If not, you will have to assemble at the end of the line with the rest. Please leave room in front of you for those with serious differences who might arrive later (almost guaranteed). 73's Richard Clark, KB7QHC |
On Fri, 26 Sep 2003 19:18:23 GMT, Richard Clark
wrote: On Fri, 26 Sep 2003 18:21:49 GMT, Gene Nygaard wrote: Now I have a challenge for you, Mr. Metrologist: Hi Gene, What are your credentials? Can one expect you have at least a degree in English? ;-) My credentials won't change what you WON'T find on the NIST web pages, wimp! Show me the official definition of a pound as a unit of force from NIST, either on their web pages or from any published document of NIST or its predecessors. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Fri, 26 Sep 2003 19:18:23 GMT, Richard Clark
wrote: On Fri, 26 Sep 2003 18:21:49 GMT, Gene Nygaard wrote: Now I have a challenge for you, Mr. Metrologist: Hi Gene, What are your credentials? Can one expect you have at least a degree in English? ;-) I am a wheat farmer who has already proved not only our resident engineer/programmer and Capital-M Metrologist wrong, but our Chief Peacekeeper Missileman Engineer as well. Isn't that enough for one week? Of course, from that job, I'm well aware of what a bushel is on the Minneapolis Grain Exchange and other commodities markets, or at the local grain elevator. It isn't a unit of volume at these places. And while it is a certain number of pounds for each particular commodity, it most certainly is not unit of force, either. Not only did I prove Mr. Metrologist wrong, but I also proved that he has no integrity. He won't even admit that I did so, even though I followed his ground rules to a T, specifically citing a NIST web page showing him to be wrong. My degrees weren't in English, however--though I did enjoy some English classes, and such a degree would have been quite relevant to our discussion of linguistics earlier. What are your credentials in linguistics? In the law, another primary subject matter of our discussion? In history? Now, find somebody on the NIST web pages with better credentials than mine and yours to tell us what the official definition of a pound force is. Still bet you can't do so. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Fri, 26 Sep 2003 19:32:28 GMT, Gene Nygaard
wrote: My credentials won't change what you WON'T find on the NIST web pages, wimp! Hi Gene, OK no credentials. No proficiency in English and not even a CB? How droll, that is indeed an amusing challenge from a middle aged farmer who would challenge where the center of North America lies. I suppose the doggerel of "a pint's a pound, the world round" bears more directly on this slim side topic - but you don't offer credentials into that. ;-) You remain inseparable (through your own choice, but not view) from any of 6 Billion who could as easily deny anything offered by me through your simple random strokes at the keyboard for rebuff. Thus fulfilling any -um- challenge is of equal magnitude in its achievement. "A learned gentleman who in the course of conversation wished to inform us of this simple fact, that the counsel upon the circuit at Shrewsbury were much bitten by fleas, took, I suppose, seven or eight minutes in relating it circumstantially. Johnson sat in great impatience till the gentleman had finished his tedious narrative, and then burst out (playfully however), 'It is a pity, Sir, that you have not seen a lion; for a flea has taken you such a time, that a lion must have served you for a twelvemonth.'" "Boswell's Life of Johnson," pg. 407 Please leave plenty of room in front of you at the end of the line. Those with credentials and important issues (and there are many, metaphorical lions as it were instead of your fleas) will no doubt (playfully however) slip in front of you in the future. 73's Richard Clark, KB7QHC |
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/ |
On Fri, 26 Sep 2003 20:45:27 GMT, Gene Nygaard
wrote: Not only did I prove Mr. Metrologist wrong, but I also proved that he has no integrity. Hi Gene, And yet this does not seem to satisfy you. ;-) No doubt this is product of an insecure basis in logic that is more heartfelt than intuitive (despite the cut-and-paste philosophies). A historical lesson is brought to bear by the publisher of Newton's Principia: 21 Nov. 1667 "I out and took coach and to Arundell house, where the meeting of Gresham College was broke up; but there meeting Creed, I with him to the tavern in St. Clements churchyard, where was Deane Wilkins, Dr. Whistler, Dr. Floyd, a divine, admitted, I perceive, this day, and other brave men. Among the rest, they discourse of a man that is a little frantic (that hath been a kind of minister, Dr, Wilkins saying that he hath read for him in his church) that is poor and a debauched man, that the College have hired for 20s. to have some of the blood of a Sheep let into his body; and it is to be done Saturday next. They purpose to let in about twelve ounces, which they compute is what will be let in in a minutes time by a watch. They differ in the opinion they have of the effects of it..." 30 Nov. 1667 "I was pleased to the see the person who had his blood taken out. He speaks well, and did this day give the Society a relation thereof in Latin, saying he finds himself much better since, and as a new man. But he is cracked a little in his head, though he speaks very reasonably and very well, He had but 20s. for his suffering it, and is to have the same tried upon him..." As I offered elsewhere; there are many in my fan club who's minds I cannot change. For such trivial matters as yours, I am afraid you have to go to the end of that line, and leave room for others of substance ahead of you. 73's Richard Clark, KB7QHC |
On Fri, 26 Sep 2003 22:20:17 GMT, Richard Clark
wrote: But he is cracked a little in his head, though he speaks very reasonably and very well Hi Gene, Knowing you need references (a classic education would have exposed this to you and it would have served no purpose to cite) Samuel Pepys. 73's Richard Clark, KB7QHC |
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 |
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) |
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