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Reposted because of server error, possible but unlikely that some get
multiple copies. wrote: I am 240 pounds 'mass' on earth. That's a fact. I am 240 pounds 'mass' on moon. That's a weird assertion! You've got me totally buffaloed now. I can't imagine what your problem is. Sure, mass is an ambiguous word, with several different meanings. But there is only one of its meanings that is normally used with numbers to express a measurement of its magnitude. If that assertion is true, who changed the density of the moon?? What in the world would the density of the moon have to do with your mass? It would be more understandable if you were having a hard time understanding the normal definitions for this particular context of the ambiguous word 'weight,' as it is quite properly and legitimately used for body weight of humans in medicine (including space medicine by NASA astronauts and doctors), and in sports, the normal reasons we weigh ourselves, and in the science of anthropology as well. Or as the word 'weight' is also used in zoology and veterinary medicine and paleontology for the weight of other animals as well as humans. Now certainly, in any of these contexts, this quantity will sometimes be referred to as 'mass' as well; that is also quite proper and legitimate. My 'weight' is 230 pounds on earth. That's a fact. My 'weight' would be 230 pounds on the earth's moon. That's also a fact. Let's review what I've already posted in other messages in this thread, from ASTM . . . thus, when one speaks of a person's weight, the quantity referred to is mass. . . . and from NIST 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 You know damn well that those kilograms are used for body weight all around the world, including most hospitals in the United States. They are indeed the proper SI units for this weight (which, as I pointed out above, is also sometimes called "mass" instead). Furthermore, as you've already seen many times over in the past few days, pounds are by definition exactly 0.45359237 kg. http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf THE REAL WORLD, AND THE REAL MOON Now let's look at something different, not dealing with imaginary transportations of you or me to the moon, but with the real world, and the real moon. What do you suppose it means when NASA tells us that the weight of the Apollo 11 Lunar Module was "10,776.6 lbs" at the time of liftoff? What ... Whoops, just about forgot where I was and got ahead of myself, forgetting that I need to slowly spell out what might be obvious to people in other newsgroups. The Lunar Module at liftoff, of course, was in actual fact located right ON THE MOON. Now, what do you suppose those pounds are? If you really have no idea how big the Lunar Module is and what its weight might be on the moon, here's a big hint. NASA also tells us that the same Lunar Module at the time of docking had a weight of 5738.0 lb. Selected Mission Weights http://history.nasa.gov/SP-4029/Apol...on_Weights.htm Where was this LM at the time of docking? That's when it caught up with the command module, where Commander Collins was at that time "weightless" in an entirely different definition of the word weight, in free-fall orbit around the moon. But not only was he not weightless in the definition being used by NASA for this LM weight, though he also was far from weightless in the definition of "weight" as a force as used by Sears and Zemansky, from whom you claim to have learned your physics. Much less in terms of force units than he would have been on Earth (about a tenth as much, only an order of magnitude guess), of course, but far from zero, in the Sears and Zemansky definition of weight. [Sears and Zemansky, 1970 page 61] 5.5 MASS AND WEIGHT The weight of a body can now be defined more generally than in the preceding chapters as the resultant gravitational force exerted on the body by all other bodies in the universe. . . . There is no general agreement among physicists as to the precise definition of "weight." Some prefer to use this term for a quantity we shall define later and call the "apparent weight" or "relative weight." In the absence of a generally accepted definition we shall continue to use the term as defined above. The NASA site discussed above, of course, is not some aberrant web page. Nor is it some alteration of the units by the NASA public affairs office--this is straight from the scientists and engineers. This is indeed normal NASA usage, to call this "weight." It is also normal NASA usage of the units "pounds." We even know that this is exactly the term under which it was programmed into their onboard computers, and the units used there as well, because we have dialogs between Ground Control and the astronauts in which they are reading out these figures for something called "weight" on both ends of the conversation, and those weights are in pounds mass. You also routinely see the same usage of the word weight when NASA talks about the weight of the space shuttles or the weight of components of the Space Station, or the weight of the spinning satellite some spacewalkers wrestled into submission a few years ago.. As an aside, what do you think: Will NASA ever learn the lesson of the Mars Climate Orbiter, and quite using pounds? -- Gene Nygaard At the present time, however, the metrical system is the only system known that has the ghost of a chance of being adopted universally by the world. -- Alexander Graham Bell,1906 |
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Roger Halstead wrote in message . ..
On Sat, 27 Sep 2003 11:48:24 GMT, Dave Shrader wrote: I am 240 pounds 'mass' on earth. That's a fact. No, in the US system of measurement your mass is measured in slugs. your weigh is measured in pounds and is 240# on earth In the metric system mass is in kg. Again the metric system is easier. 240#=109.091 kg If you expect to sound like you have some expertise in this area, I suggest you study up on precision, on significant digits and the like. You can't start with a mass with only 2 or 3 at the most significant digits, and get a conversion accurate to 6 significant digits. Furthermore, if he were 240.000 lb, then he would be 108.862 kg, not 109.091 kg. You also cannot use a conversion factor with only 2 or 3 significant digits, and get a result with six significant digits (you used 1 kg = 2.2 lb, whereas the actual definition of a pound is exactly 0.45359237 kg). I am 240 pounds 'mass' on moon. That's a weird assertion! Your mass is still the same (109.091 kg), but your weight is considerably less on the moon. His mass is still the same, 240 lb, is every bit as true. What's this bull**** about mixing together pounds and kilograms in a totally confusing and stupid system of units? After all, your claim above was that "in the US system of measurement your mass is measured in slugs" so why aren't you using these units? Yes, if his mass is 240 lb, you could also say that his mass is 7.5 slugs. But by the same token, you could use one of the old non-SI metric systems, and say that his mass is 11.1 hyls, in the system in which the base units are the meter for length, the kilogram for force, and the second for time. But the existence of the hyl does not prove that kilograms are not units of mass. By the same token, the existence of the slug does not prove that pounds are not units of mass. Each of those units, the slug and the hyl (aka the metric slug), exist in only one particular subset of units, a subset which forms a coherent system of units like SI, in which there is only one unit for each different quantity and that unit is a unitary combination of the base units. The only system which uses slugs is normally identified as the English (or British, this identifier being a matter of history and derivation), or the U.S. (because it is also used here) "gravitational foot-pound-second system of units." Your characterization of it as "the U.S. system" is vague and misleading, overly broad. The only system which has slugs excludes many of the units used in the United States, such as pints and gallons and bushels and horsepower and Btu and miles and ounces and psi. If that assertion is true, who changed the density of the moon?? It has nothing to do with the assertion, but the mass of the moon is less than the mass of the earth. The mass of the Earth is in fact 81.3 times that of the earth's moon, and you are right, it has absolutely nothing to do with what Dave Shrader was talking about. The mass of you and the earth sets what you weight on earth. Your mass and the mass of the moon set what you weigh on the moon. The No. Even accepting that you are using a force definition of the ambiguous word weight (IOW, a definition nonstandard for the context of body weight), there is one other factor that is also especially important. After all, remember that I told you above that the mass of the Earth is 81.3 times the mass of the moon. Do you think that the force due to gravity that an object exerts on Earth will be 81.3 times the force that the same object would exert on the moon? What do you suppose that other important factor might be (hint--while the force varies only linearly with mass, it varies in inverse proportion to the square of this other factor). mass of the moon is much less than that of earth so you weight much less on the moon. -- Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ "It's not the things you don't know what gets you into trouble. "It's the things you do know that just ain't so." Will Rogers |
Gene Nygaard wrote:
"You are talking about something different from mass." Yes. An orbiting astronaut may be weightless due to a particular balance of forces, but he has mass and inertia. We have weight and force. Either weight or force may be expressed in pounds or kilograms. The conversion number I remember and use is: 2.2 pounds equal 1 kilogram. The dictionary says the kilogram is a unit of mass, since a mass can conveniently be accurately represented by an object. That particular object is a cylinder of platinum-iridium alloy, called the international prototype kilogram. This object is preserved in a vault at Sevres, France. Work may be meaasured as force times distance or as pounds times feet. Power is work per unit time. Power may be expressed as foot-pounds per minute. James Watt`s horse was said capable of working at a rate of 33,000 foot-pounds per minute. I calculate that as 250 kilogram-feet per second or 76.2 kilogram-meters per second. Best regards, Richard Harrison, KB5WZI |
On Fri, 26 Sep 2003 22:20:17 GMT, Richard Clark
wrote: 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). snip 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. We've already heard the same lame excuse three times before. Translation (from the point of view of Mr. Metrologist, aka R. Clark): I already wasted three hours searching through the NIST web site for a definition of a pound, and I couldn't find one either as a unit of force or as a unit of mass. So I didn't figure that some whippersnapper who just popped into this thread would be able to find any official definition of the pound as a unit of mass there. Okay, so he proved me wrong about pounds as units of mass. But I'll be damned if he's going to get me admit that there isn't any official definition of a pound force on NIST's pages. end of translation There, I told them anyway. BTW, though I can't find an "official" definition of a pound force on NIST's pages, I can find a conditional one, with a big "if" indicating fairly clearly that the pound force has never been officially defined. Can anyone else even find that one? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Sun, 28 Sep 2003 13:44:48 GMT, Gene Nygaard
wrote: We've already heard the same lame excuse three times before. Hi Gene, So how deep do I have to plant it before it takes root? ;-) Like this compulsive interest with your fleas, you have written a Gregorian Mass that consists of only one note. To your advantage, if you had transposed "Old MacDonald Had a Farm"; then the monotonic rendition would at least give the appearance of CW. You are dreadfully out of your element here. Given the low intellectual bandwidth offered by your specious claims, I can sit back and enjoy some stylistic variations to exercise my fingers at the keyboard. I especially enjoy your barnyard epithets - such a self fulfilling cliche inspires my anecdotes. Here's another that a liberal education would have exposed you to (if only): 21 Nov. 1667 "On this occasion Dr. Whistler told a pretty story related by Muffett, a good author, of Dr. Cayus that built Key's College: that being very old and lived only at that time upon woman's milk, he, while he fed upon the milk of a angry fretful woman, was so himself; and then being advised to take of a good natured woman, he did become so, beyond the common temper of his age." Oh, if you missed the citation to the quote above, that was again from Samuel Pepys (same day in fact) who, although not trained in the sciences, did learn to respect others of learning and accomplishment. And by the way, that earlier quote: 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 Contains a Pound reference you obviously missed (from the exchange rate of 20 Shillings). Now, as every good Englishman would have understood back then, this was a conversion. If he held 20 coins they were NOT a Pound which is a single coin. There is an equivalency, but this does not constitute an equality. Pepys could have written 1£ that is shorter, but he did not as it was obviously not what was tendered to the debauched man. Even the debauched man would understand the significance of weight v. mass and how equivalencies of 1pound = umpty-ump grams does not render the term pound as mass, merely an antiquated variant much like 10000 swallows' tongues = 1KG. Shirley you don't consider swallows' tongues as units of mass? Cow tongues (Neat's tongue to the English) perhaps. And this leads us back to the good Dr. Cayus' condition - perhaps you should change your diet. The folks at the end of the line are beginning to complain - could you move back some more? 73's Richard Clark, KB7QHC |
On Sun, 28 Sep 2003 18:04:26 GMT, Richard Clark
wrote: 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 Contains a Pound reference you obviously missed (from the exchange rate of 20 Shillings). Now, as every good Englishman would have understood back then, this was a conversion. If he held 20 coins they were NOT a Pound which is a single coin. There is an equivalency, but this does not constitute an equality. Pepys could have written 1£ that is shorter, but he did not as it was obviously not what was tendered to the debauched man. Hi All, The application of the monetary unit is not without is antecedents in weight. The ancients, that is the pre-Newtonians, did not comprehend the separable notion of mass from weight as they did not accept the concept of "force" which was largely rejected by scientists of Newton's day. In fact, Newton introduced the notion of forces in his treatise "Opticks." However, to return to the legacy of £. The symbol is drawn from Libra. I have already discussed the operation of the balance scale and its relationship to Libra is evident in the astrological application. Libra (as is the latinate pondo) was the unit of weight (not scientific mass, they had no such distinction) in ancient Rome. I notice that our correspondent who relies on scientific cut-and-paste retorts to dismiss scientific workers; and, as an acknowledged untutored English speaker (several classes notwithstanding) also leverages dictionaries to the same poor quality of transliteration. The OED (which I am sure to get copious and unreliable rebuttal to) offers of "mass" a physics application buried quite deeply within the usage of this word across time (the OED is a dictionary of enumerated usage by time, not by current application). For many hundreds of years, mass merely meant the agglomeration of stuff (it didn't matter what or why). Through the work of Newton's introduction of the concept of force, the term, by OED account, then gained a distinction such that they offer the definition: "6.b. Physics. The quantity of matter which a body contains; in strict use distinct from weight. 1704" This is a pleasurable aside, these side bars of minutia to our usual concerns. A do enjoy the drama queens that our group attracts and the revisionist logic that attends their petty issues. Forgive me Gene, but you don't have much else to offer and you will be gone soon anyway, so go away mad (to invert an old saw). ;-) 73's Richard Clark, KB7QHC |
On Sun, 28 Sep 2003 18:04:26 GMT, Richard Clark
wrote: Given the low intellectual bandwidth offered by your specious claims, Still dreaming that somebody is going to come to your rescue, and show us some NIST web page giving an _official_ definition of a pound as a unit of force, aren't you? Wake up and smell the coffee! It isn't going to happen, for several reasons, including 1. Your research skills are better than those of most others following this thread, and 2. You are better able to distinguish "swallow's tongue" conversion factors from official definitions, and 3. They don't have a reputation to reconstruct, and 4. They don't know people at NIST that they can call on for help in this search for the official definition, and 5. You've got them all convinced that you are an expert in this area, and everyone expects that you could easily prove your point, and 6. A lot of people who know more about this than you do have unsucessfully searched for an official definition, and 7. Dr. Barry Taylor, the NIST expert in this particular field who must be a METROLOGIST if you are a mere capital-M Metrologist, is the one who gives us the conditional definition which is a clear indicator that an official definition does not exist. Face the facts. Hard as it might be to believe (even for me, when I first came to this realization!), THERE IS NO SUCH OFFICIAL DEFINITION OF A POUND FORCE. Nobody has ever gone to the trouble of officially defining these ******* offspring of pounds as units of mass, and nobody will bother doing so in the future. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Sun, 28 Sep 2003 22:10:13 GMT, Gene Nygaard
wrote: Wake up and smell the coffee! Hi Gene, You've missed one point (beyond I am not a coffee drinker) to which I can respond: I don't give a damn. :-) Your condescending attitude towards others all convinced that you are an expert is obviously spun from your imagination as absolutely no one here has commented for me, with me, to me, or about me (your QRM hardly allows them that). As for reputation.... You, admittedly, have absolutely no experience in the matter, and this is not rec.sci.amateur.hour. Given your petulance out of the gate discussing the subject, you don't even qualify for honorary troll. You have no style, and the cut-and-paste philosophy runs thick in this group as it is. Yours certainly is no more distinctive, and when it is laid out by the ream like so much textual fertilizer, it won't grow the crops to save the farm. C'mon now Gene, we both know what I have to say on the matter is wholly irrelevant to how you are going to boast about it around town. Sort of like the tailor who wore on his belt "Killed seven with one blow" and was only boasting about flies while gushing it up about giants. Talk about (emphasis on talk) reputations made. ;-) 73's Richard Clark, KB7QHC |
On Mon, 29 Sep 2003 05:30:51 GMT, Richard Clark
wrote: As for reputation.... You, admittedly, have absolutely no experience in the matter, and this is not rec.sci.amateur.hour. I live in one of the windiest parts of the country, and I am quite capable of recognizing the sound of hot air rushing by. If there is, in fact, an official definition of the pound as a unit of force, it isn't going to be a closely guarded secret, even post-11 Sep 2001. If you are a Metrologist, it should be a piece of cake to find it. So for you, or anyone else who would like to help you out, here are a few hints. Some of you likely are or have been science teachers. Use the resources you have at hand to find this elusive official definition of the pound as a unit of force. Tell me exactly what the standard is, who defined it, and when. Or go to someone you had as a science teacher, and enlist their help. Go to a science teacher who is teaching your kids or grandkids. Look in the textbooks you used, and see if the authors have any footnotes citing the authority for whatever definition they use. Look for the official definition in the CRC Handbook of Chemistry and Physics, or in the Engineer's Handbook. Look for the official definition in Encyclopædia Britannica, or in World Book Encyclopedia, or the World Almanac, and whatever source is cited in any of these. Write or email NIST, and be sure to ask them not only what the official definition is, but what makes it official and how long it has been in use. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Sun, 28 Sep 2003 18:04:26 GMT, Richard Clark
wrote: Pepys could have written 1£ that is shorter, but he did not as it was obviously not what was tendered to the debauched man. Even the debauched man would understand the significance of weight v. mass and how equivalencies of 1pound = umpty-ump grams does not render the term pound as mass, Let me explain to you the difference between your mere equivalence and a definition. At the same time the pound was redefined around the world as 0.45359237 kg, the yard was redefined as 0.9144 m. Since then, no specific action has ever been taken to redefine the yard, yet its ultimate definition has changed not just once but twice. When the yard was redefined as 0.9144 m in 1959, exactly 2 parts per million less than the old U.S. definition, the meter was defined by the distance between two lines on a certain platinum-iridium bar with a Tresca (crooked x) cross-section, kept by the BIPM at the same location where the official kilogram is kept. The yard was then 0.9144 times the distance between those two marks. Then in 1960 the meter was redefined as 1650763.73 wavelengths of the orange-red emission line emitted by a certain transition in krypton-86 atoms. Thus, at that time the yard was ultimately defined as 1509458.354712 wavelengths of the same light. Then in 1983 the definition of the meter was changed, making it so the speed of light in a vacuum is exactly 299792458 meters per second. No action was taken to change the definition of a yard, but it changed nonetheless. A yard is now ultimately defined, for the present time and until and if the meter definition ever changes again, as the distance that light travels in a vacuum in 1143/374740572500 second. On the other hand, suppose that one or all of the countries involved choose to abrogate the 1959 redefinition of the yard in terms of the meter, and instead restore some independent standard. What effect would that have on the ultimate definition of the meter? None whatsoever. Likeways, if the kilogram were to be redefined as x buckyballs of carbon-12, then the pound would automatically become 0.45359237x buckyballs of carbon-12. OTOH, if someone restored the definition of the pound to some independently maintained chunk of metal, that would have no effect whatsoever on the definition of the kilogram, and the realtionship between the pound and the kilogram would then become a measured quantity rather than an exact definition. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Mon, 29 Sep 2003 13:18:36 GMT, Gene Nygaard
wrote: On Mon, 29 Sep 2003 05:30:51 GMT, Richard Clark wrote: As for reputation.... You, admittedly, have absolutely no experience in the matter, and this is not rec.sci.amateur.hour. I live in one of the windiest parts of the country, and I am quite capable of recognizing the sound of hot air rushing by. If there is, in fact, an official definition of the pound as a unit of force, it isn't going to be a closely guarded secret, even post-11 Sep 2001. If you are a Metrologist, it should be a piece of cake to find it. So for you, or anyone else who would like to help you out, here are a few hints. Some of you likely are or have been science teachers. Use the resources you have at hand to find this elusive official definition of the pound as a unit of force. Tell me exactly what the standard is, who defined it, and when. Or go to someone you had as a science teacher, and enlist their help. Go to a science teacher who is teaching your kids or grandkids. Look in the textbooks you used, and see if the authors have any footnotes citing the authority for whatever definition they use. Look for the official definition in the CRC Handbook of Chemistry and Physics, or in the Engineer's Handbook. Look for the official definition in Encyclopædia Britannica, or in World Book Encyclopedia, or the World Almanac, and whatever source is cited in any of these. Write or email NIST, and be sure to ask them not only what the official definition is, but what makes it official and how long it has been in use. More possibilities-- Go to sci.physics or slug.support and ask the people there to point you to the official definition of the pound as a unit of force. Search Lexis (http://www.lexis-nexis.com) for a legal definition, if you are a subscriber to this service or know someone who has access to it. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
Gene wrote,
Some of you likely are or have been science teachers. Use the resources you have at hand to find this elusive official definition of the pound as a unit of force. Tell me exactly what the standard is, who defined it, and when. I'm not a science teacher, but it wasn't hard to find. Look in the _Handbook of Mathematical Functions_ under "Physical Constants and Conversion Factors," by A.G. McNish of the National Bureau of Standards (this is an old book). There it is, clear as a drunkard's gin, 1 pound force = 4.44822 Newtons. Speaking of Newtons, Newton, is the catty a unit of weight, force, or mass, and where is the official definition of same? What! No official definition of a unit that has been in use for thousands of years? Why are you arguing about old measurement standards on a newsgroup that is supposed to be devoted to the amateur use of antennas? There should be a newsgroup devoted to the obsessions of amateur physicists where like-minded people could rail at one another without bothering anyone else. You should understand that there are very few people in the world who ever bother to let the concept of pound force disturb their sleep at night. Perhaps you shouldn't let it bother yours, either. 73, Tom Donaly, KA6RUH |
On 29 Sep 2003 15:08:27 GMT, (Tdonaly) wrote:
Gene wrote, Some of you likely are or have been science teachers. Use the resources you have at hand to find this elusive official definition of the pound as a unit of force. Tell me exactly what the standard is, who defined it, and when. I'm not a science teacher, but it wasn't hard to find. Look in the _Handbook of Mathematical Functions_ under "Physical Constants and Conversion Factors," by A.G. McNish of the National Bureau of Standards (this is an old book). There it is, clear as a drunkard's gin, 1 pound force = 4.44822 Newtons. Speaking of Newtons, How old? When was it published (before or after 1959, in particular). I will bet that Richard Clark won't endorse your finding as being any sort of "official definition." What do you say, Richard? Did he find a hidden treasure? McNish also gives a conversion factor for pounds to kilograms, doesn't he? From what you have given us, he identified the "pounds force" as such. What does he call the pounds which are converted to kilograms? Just "pounds"? Or "pounds mass"? Or just "pounds avoirdupois" and "pounds troy" without saying that they are pounds mass? I'll also bet that McNish didn't call them "Newtons"--it is newtons, not capitalized in English. Now, let's assume that this were an official definition. Then what is the "standard acceleration of gravity" in English units? A pound force is equal to a pound mass times the standard acceleration of gravity. We already know a pound is officially defined as 0.45359237 kg, so that standard acceleration of gravity will be 1 lbf divided by 1 lb. 1 lbf/1 lb =4.44822 N/0.45359237 kg = (4.44822 kg m/s²)/0.45359237 kg = 4.44822/0.45359237 m/s² or about 9.80664643896 m/s² (4.44822/0.45359237 m/s²)(1 ft/0.3048 m) = 4.44822/0.138254954376 ft/s² = 32.17403687... ft/s² That is indeed awfully close to the standard acceleration of free fall which is official for defining kilograms force. But it isn't the same, if that is an official definition of a pound force. Newton, is the catty a unit of weight, force, or mass, and where is the official definition of same? What! No official definition of a unit that has been in use for thousands of years? There are lots of official definitions--but since I don't read Chinese, I'm not about to venture a guess as to whether or not any of them are found on the Internet. They are units of mass, of course. Originally represented by independently maintained standards, and varying somewhat in different countries. Just as pounds were and just as kilograms still are. But at various times and places, and for various purposes such as international trade, catties were officially redefined in several different ways: as exactly 1 1/3 lb avoirdupois, as exactly 600 g, and as exactly 500 g are just a few of those official redefinitions--there might also have been one in terms of troy units, perhaps 20 oz troy = 1 2/3 lb troy, and perhaps other redefinitions in terms of either Spanish or Portuguese libras. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Mon, 29 Sep 2003 15:53:34 GMT, Gene Nygaard
wrote: I will bet that Richard Clark won't endorse your finding as being any sort of "official definition." What do you say, Richard? Did he find a hidden treasure? Hi Gene, You haven't got it yet? I don't care. :-) Your correspondence with its one note tune reminds me of the couplet about fleas "and fleas have littler fleas, and so on ad infinitum" 73's Richard Clark, KB7QHC |
On 29 Sep 2003 15:08:27 GMT, (Tdonaly) wrote: Gene wrote, Some of you likely are or have been science teachers. Use the resources you have at hand to find this elusive official definition of the pound as a unit of force. Tell me exactly what the standard is, who defined it, and when. I'm not a science teacher, but it wasn't hard to find. Look in the _Handbook of Mathematical Functions_ under "Physical Constants and Conversion Factors," by A.G. McNish of the National Bureau of Standards (this is an old book). There it is, clear as a drunkard's gin, 1 pound force = 4.44822 Newtons. Speaking of Newtons, How old? When was it published (before or after 1959, in particular). I will bet that Richard Clark won't endorse your finding as being any sort of "official definition." What do you say, Richard? Did he find a hidden treasure? McNish also gives a conversion factor for pounds to kilograms, doesn't he? From what you have given us, he identified the "pounds force" as such. What does he call the pounds which are converted to kilograms? Just "pounds"? Or "pounds mass"? Or just "pounds avoirdupois" and "pounds troy" without saying that they are pounds mass? I'll also bet that McNish didn't call them "Newtons"--it is newtons, not capitalized in English. Now, let's assume that this were an official definition. Then what is the "standard acceleration of gravity" in English units? A pound force is equal to a pound mass times the standard acceleration of gravity. We already know a pound is officially defined as 0.45359237 kg, so that standard acceleration of gravity will be 1 lbf divided by 1 lb. 1 lbf/1 lb =4.44822 N/0.45359237 kg = (4.44822 kg m/s²)/0.45359237 kg = 4.44822/0.45359237 m/s² or about 9.80664643896 m/s² (4.44822/0.45359237 m/s²)(1 ft/0.3048 m) = 4.44822/0.138254954376 ft/s² = 32.17403687... ft/s² That is indeed awfully close to the standard acceleration of free fall which is official for defining kilograms force. But it isn't the same, if that is an official definition of a pound force. Gene wrote, Newton, is the catty a unit of weight, force, or mass, and where is the official definition of same? What! No official definition of a unit that has been in use for thousands of years? There are lots of official definitions--but since I don't read Chinese, I'm not about to venture a guess as to whether or not any of them are found on the Internet. They are units of mass, of course. Originally represented by independently maintained standards, and varying somewhat in different countries. Just as pounds were and just as kilograms still are. But at various times and places, and for various purposes such as international trade, catties were officially redefined in several different ways: as exactly 1 1/3 lb avoirdupois, as exactly 600 g, and as exactly 500 g are just a few of those official redefinitions--there might also have been one in terms of troy units, perhaps 20 oz troy = 1 2/3 lb troy, and perhaps other redefinitions in terms of either Spanish or Portuguese libras. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ That's the kind of reply I expected. You didn't reply, however, to my contention that your posts are off topic and excessively obsessive. I'd like to know something, though. What made you believe that anyone here would be interested in your petty distinction between pounds and pounds? I expect Richard is enjoying himself, as he collects much laughter up the sleeve, but I think the whole thing is strange, even for this newsgroup. 73, Tom Donaly, KA6RUH |
On Mon, 29 Sep 2003 16:38:03 GMT, Richard Clark
wrote: On Mon, 29 Sep 2003 15:53:34 GMT, Gene Nygaard wrote: I will bet that Richard Clark won't endorse your finding as being any sort of "official definition." What do you say, Richard? Did he find a hidden treasure? Hi Gene, You haven't got it yet? I don't care. :-) Gee, I forgot. I suppose 14 responses are pretty good evidence of how little you do care. If anybody actually does come up with an official definition, you'll be latching onto it like a fly onto ****. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
Richard Clark wrote:
"The folks at the end of the line are beginning to complain - could you move back some more?" Could Richard Clark be referring to Stan Freburg`s parody of Harry Belafonte`s "Banana Boat Song" (Day-O, Day-O, etc)? Some more! They can still hear you! Best regards, Richard Harrison, KB5WZI |
On Mon, 29 Sep 2003 13:56:50 GMT, Gene Nygaard
wrote: Let me explain to you the difference between your mere equivalence and a definition. Hi Gene, You admittedly don't have the skills (which is evident in the single sentence quote above). And further, you say nothing responsive to the post, instead, yet again repeating, ad nauseum, the same poor quality of scripted response. You are out of your element and terribly devoid of communication concepts that go beyond a cut-and-paste philosophy. Your knee jerk response to label any intelligent response as being offered by a fool is no retort of substance here. I willingly embrace such a title of fool. You can easily consult Google to the matter, but I will repeat it for you: "Considering how many fools can calculate, it is surprising that it should be thought either a difficult or a tedious task for any other fool to learn how to master the same tricks. "Some calculus-tricks are quite easy, Some are enormously difficult. The fools who write the text-books of advanced mathematics - and they are the most clever fools - seldom take the trouble to show you how easy the easy calculations are. On the contrary, they seem to desire to impress you with their tremendous cleverness by going about it in the most difficult way. "Being myself a remarkably stupid fellow, I have had to unteach myself the difficulties, and now beg to present to my fellow fools the parts that are not hard. Master these thoroughly, and the rest will follow. What one fool can do, another can." Silvanus P. Thompson, F.R.S. If this seems a little dense in its meaning, it suggests the totality of your intellectual achievement in 3000+ posts can be contained in a handheld calculator with that calculator's added benefit that it won't back sass the operator. :-) C'mon now Gene, we both know that any perceived admission to your inestimable authority would deflate you immediately into the depression of not being the focus - merely the period ending a lengthy, but trivial unread footnote. The web is littered with similar academic wannabees. Your one note opera doesn't even need the fat lady. Curtain. 73's Richard Clark, KB7QHC |
Gene Nygaard wrote: My 'weight' is 230 pounds on earth. That's a fact. My 'weight' would be 230 pounds on the earth's moon. That's also a fact. Your weight is defined as what you weigh on Earth, assuming a gravitational acceleration of g. Obviously it's not true that your weight would be measured as 230 pounds on the moon. The CRC Handbook of Chemistry and Physics states that the weight of a body varies with location, and defines weight as W = mg, where g is the local acceleration due to gravity. Reflecting the apparent dichotomy, the CRC defines the pound both ways: "1. A unit of mass equal in the U.S. to 0.45359237 kg. exactly. 2. Specifically, a unit of measurement of the thrust or force of a reaction engine representing the weight the engine can move, as an engine with 100,000 pounds of thrust. 3. The force exerted on a one pound mass by the standard acceleration of gravity." Interestingly, they also define poundal, pound mass and pound weight. No mention of pound force. Evidently, that would be redundant. ;-) As an aside, what do you think: Will NASA ever learn the lesson of the Mars Climate Orbiter, and quite using pounds? Actually the contractor had specified the thrust of its rocket motor in pounds. NASA failed to properly convert to the CGS system that it (and most other scientific organizations) normally use. 73, Jim AC6XG |
On Mon, 29 Sep 2003 16:51:55 GMT, Gene Nygaard
wrote: You haven't got it yet? I don't care. :-) Gee, I forgot. If anybody actually does come up with an official definition, you'll be latching onto it like a fly onto ****. Hi Gene, Suffering from www.Alzheimer's? You dropped the cue in the space of one line. :-) You really need to read Tom's comment. Your return to barnyard epithets again reinforces the fulfilled cliché of the bumpkin. Our comparison of credentials does serve a useful purpose, n'est pas? My sleeve runneth over. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
"Silvanus P. Thompson, F.R.S." Anyone who can present a subject so simply and logically as Thompson does in "Calcus Made Easy", Second Edition Enlarged, The Macmillan Company, 1951, for the 21st printing, October 1914 for the 2nd edition release, truly understands his subject. Thompson also says: "There are 60 minutes in the hour, 24 hours in the day, 7 days in the week. There are therefore 1440 minutes in the day and 10080 in the week." This leaped off the page for me after the 12 pence to the shilling, 20 shillings to the pound, etc in an earlier posting. Different names and unit sizes for the same item. It`s the same for baloney. No matter how thin you slice it it`s still baloney. Kilograms and pounds are also different names and unit sizes for the same items, mass and force. Kilograms and pounds readily exchange when using the proper rates. Best regards, Richard Harrison, KB5WZI |
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On Mon, 29 Sep 2003 17:29:54 GMT, Richard Clark
wrote: On Mon, 29 Sep 2003 16:51:55 GMT, Gene Nygaard wrote: You haven't got it yet? I don't care. :-) Gee, I forgot. If anybody actually does come up with an official definition, you'll be latching onto it like a fly onto ****. Hi Gene, Suffering from www.Alzheimer's? You dropped the cue in the space of one line. :-) You really need to read Tom's comment. It's good to see that you have enough integrity left not to claim that the old NBS conversion factor which Tom found (which differs from the conditional definition given by Dr. Barry Taylor of NIST in 1995) is the *official* definition of a pound as a unit of force. Even if you were deceitfully hoping that some of the others in this thread would misinterpret that last-quoted statement that way. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Sun, 28 Sep 2003 19:39:53 GMT, Richard Clark
wrote: Hi All, Star Avoirdupois Pound http://museum.nist.gov/object.asp?ObjID=10 Hassler constructed troy pounds and avoirdupois pounds, for distribution to the custom-houses and to the States. The mass of a troy pound is 0.82286 of an avoirdupois pound's mass. The troy pound is used for determining the mass of precious metals. Hassler used the troy pound of the U.S. Mint in Philadelphia, procured in London in 1827 by Albert Gallatin, to derive both types of standards. It is likely that the Star Avoirdupois Pound (so named because of the star inscribed on top of its knob) is the avoirdupois pound that was directly derived from the Mint Pound by Hassler. http://museum.nist.gov/exhibits/ex1/Room2.html Ferdinand Rudolph Hassler was appointed the first Superintendent of the Survey of the Coast by President Madison in 1816. Born in Aarau, Switzerland in 1770, Hassler emigrated to the United States in 1805. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
Gene Nygaard wrote:
"Look in the textbooks you used, and see if the authors have any footnotes citing the authority for whatever definition they use. My Random House American College Dictionary (circa 1950) says: "kilogram, n. Metric System. a unit of mass and weight, equal to 1000 grams and equivalent to 2.2046 pounds avoirdupois. For pounds, the same dictionary says: "Pound. 1. a unit of weight and of mass, varying in different periods and countries. Pounds and kilograms are different units for the same things, force and weight. Rants in this thread are inane. The world gets by just fine using 2.2046 pounds equal 1 kilogram. The question, "Which is heavier - a pound of gold or a pound of feathers?" A pound of feathers is heavier than a pound of gold because gold is measured in troy pounds while feathers are measured in avoirdupois pounds. Troy pounds have 12 ounces; avoirdupois pounds have 16 ounces. A troy pound contains 372 grams in the Metric System: an avoirdupois pound contins 454 grams. Each troy ounce is heavier than an avoirdupois ounce, says "The Handy Science Answer Book". Baloney is sliced thinly above, but it`s still baloney. Best regards, Richard Harrison, KB5WZI |
On Mon, 29 Sep 2003 23:38:14 -0500 (CDT),
(Richard Harrison) wrote: Gene Nygaard wrote: "Look in the textbooks you used, and see if the authors have any footnotes citing the authority for whatever definition they use. My Random House American College Dictionary (circa 1950) says: "kilogram, n. Metric System. a unit of mass and weight, equal to 1000 grams and equivalent to 2.2046 pounds avoirdupois. For pounds, the same dictionary says: "Pound. 1. a unit of weight and of mass, varying in different periods and countries. Pounds and kilograms are different units for the same things, force and weight. Still haven't figured out that your claims that both kilograms and pounds are names of both a unit of mass and a unit of force is at odds with what Dave Shrader and Richard Clark have been telling us, have you? Of course, kilograms force were also still quite acceptable units in 1950 when your dictionary was written, before the International System of Units was introduced in 1960. Rants in this thread are inane. The world gets by just fine using 2.2046 pounds equal 1 kilogram. In 1950, that's about as good as they could do--more precise expressions of this equivalence would have required specifying the location in which the avoirdupois pounds were used. That changed in 1959, when the national standards laboratories of the six major countries using English units got together and defined the pound as 0.45359237 kg. But people who care about what they are doing also know that this conversion factor doesn't work for pounds force, which are converted to newtons rather than to kilograms in the modern metric system. The question, "Which is heavier - a pound of gold or a pound of feathers?" A pound of feathers is heavier than a pound of gold because gold is measured in troy pounds while feathers are measured in avoirdupois pounds. Troy pounds have 12 ounces; avoirdupois pounds have 16 ounces. A troy pound contains 372 grams in the Metric System: an avoirdupois pound contins 454 grams. Each troy ounce is heavier than an avoirdupois ounce, says "The Handy Science Answer Book". You missed the most important difference between troy pounds and avoirdupois pounds. The troy units of weight are always units of mass, never units of force. The avoirdupois units of weight were units of mass from the beginning, but they recently spawned a unit of force of the same name (a unit that was never well defined before the 20th century, when people first started using a "standard acceleration of gravity"). Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Mon, 29 Sep 2003 10:12:33 -0700, Jim Kelley
wrote: Gene Nygaard wrote: My 'weight' is 230 pounds on earth. That's a fact. My 'weight' would be 230 pounds on the earth's moon. That's also a fact. Your weight is defined as what you weigh on Earth, assuming a gravitational acceleration of g. Obviously it's not true that your weight would be measured as 230 pounds on the moon. The CRC Handbook of Chemistry and Physics states that the weight of a body varies with location, and defines weight as W = mg, where g is the local acceleration due to gravity. It doesn't cost you any more to pay attention. Repeat to yourself until you understand it: Weight is an AMBIGUOUS word. IT HAS SEVERAL DIFFERENT MEANINGS. The one you cite from the Chemical Rubber Company is, of course, one of those several definitions. If it always meant the same as mass in physics jargon, I wouldn't have to point out to you that this is an ambiguous word, would I? Didn't you read the message you responded to, especially what immediately followed the sentence you quoted? Didn't you see what NIST and ASTM have to say about this? Look at it again, and read it slowly this time Let's review what I've already posted in other messages in this thread, from ASTM . . . thus, when one speaks of a person's weight, the quantity referred to is mass. . . and from NIST 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 Learn to evaluate your sources, also. Those sources are more credible than any CRC Handbook on this subject. Your definition of weight is not the proper one to use for your body weight in the doctor's office or the gym. It is not the one used in our hospitals. It is not the one used in weighing an NFL lineman at 380 lb, which is equal to 0.98 slinches in one system or 11.8 slugs in another system of those strange units only used in calculations, only in the sciences, and only in North America to any significant extent (people in other English-units countries continued to use the absolute fps system with force in poundals until they converted to the metric system in their engineering). You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. But keep in mind that if you do make that voluntary decision, that fact doesn't prove that anyone else is making an error if they call it "weight." Furthermore, it is not an acceptable option to misinterpret what they are saying, and to misapply an inappropriate definition of weight. You could, of course, argue that we should all change to your usage. But you certainly aren't going to exert the effort that would be necessary get us to give up a word to which we have a prior claim, if you aren't smart enough to figure out that it would be a change. Furthermore, to have any hope of success, you'd have to offer us a verb as well as a noun. Reflecting the apparent dichotomy, the CRC defines the pound both ways: "1. A unit of mass equal in the U.S. to 0.45359237 kg. exactly. 2. Specifically, a unit of measurement of the thrust or force of a reaction engine representing the weight the engine can move, as an engine with 100,000 pounds of thrust. 3. The force exerted on a one pound mass by the standard acceleration of gravity." That really shouldn't come as any surprise to you, does it, at this stage of the game? Interestingly, they also define poundal, pound mass and pound weight. No mention of pound force. Evidently, that would be redundant. ;-) Have you figured out yet what those poundals are, and how they are used? What is the base unit of mass in the system in which these force units are used? One thing about the CRC Handbook (which edition?) is that they include stuff put in there over a period of many years, most of it undated. Those "pounds weight" are an obsolete term for what are now called pounds force. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
Gene Nygaard wrote:
You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. Here's an interesting quote from _University_Physics_ by Young and Freedman: "On the moon, a stone would be just as hard to throw horizontally, but it would be easier to lift." It also says weight is a vector and mass is a scalar. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil wrote,
Gene Nygaard wrote: You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. Here's an interesting quote from _University_Physics_ by Young and Freedman: "On the moon, a stone would be just as hard to throw horizontally, but it would be easier to lift." It also says weight is a vector and mass is a scalar. -- 73, Cecil http://www.qsl.net/w5dxp You better watch out, Cecil, Gene is liable to write a scathing indictment of your intelligence, integrity, and job fitness, for quoting that. By the way, what ever happened to the old idea that the attraction between two masses was directly proportional to the size of the two masses multiplied together, and inversely proportional to the square of the distance between them - sort of like positive and negative charge (Coulomb's Law and all that). 73, Tom Donaly, KA6RUH |
Cecil, W5DXP wrote:
"On the moon, a stone would be just as hard to throw horizontally, but it would be easier to lift." The normal forces are different on the earth and moon. But, the physics book statement follows from Newton: F= MA, and M is the same on earth or moon. Best regards, Richard Harrison, KB5WZI |
Richard Harrison wrote: Cecil, W5DXP wrote: "On the moon, a stone would be just as hard to throw horizontally, but it would be easier to lift." The normal forces are different on the earth and moon. But, the physics book statement follows from Newton: F= MA, and M is the same on earth or moon. I think the point is that the inertia is the same, independent of what the gravity might happen to be, thus demonstrating the most fundamental property and defining feature of mass. 73, Jim AC6XG |
Gene Nygaard wrote:
It doesn't cost you any more to pay attention. Repeat to yourself until you understand it: Weight is an AMBIGUOUS word. IT HAS SEVERAL DIFFERENT MEANINGS. What cause have I given you to write to me in such a manner? The one you cite from the Chemical Rubber Company is, of course, one of those several definitions. If it always meant the same as mass in physics jargon, I wouldn't have to point out to you that this is an ambiguous word, would I? This is the first you've mentioned anything about it being ambiguous. Until now, you've just been belligerent and accusational about it. Didn't you read the message you responded to, especially what immediately followed the sentence you quoted? Didn't you see what NIST and ASTM have to say about this? Look at it again, and read it slowly this time I'm commenting on what you said, Gene. I have no comment on what NIST had to say. 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 Learn to evaluate your sources, also. Those sources are more credible than any CRC Handbook on this subject. You need to learn how to attribute yours. I didn't write that. :-) Your definition of weight is not the proper one to use for your body weight in the doctor's office or the gym. I don't write definitions. But the ones I have cited are no less accurate in the doctors office than the physics lab. You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. As I recall, the argument was about whether to call it a mass or a force. It's generally accepted that weight is a force. Problems can arise when someone claims a mass is a force and vice versa. Furthermore, it is not an acceptable option to misinterpret what they are saying, and to misapply an inappropriate definition of weight. It is possible that you are doing some of the misinterpreting. You could, of course, argue that we should all change to your usage. Many people already have, obviously. Reflecting the apparent dichotomy, the CRC defines the pound both ways: "1. A unit of mass equal in the U.S. to 0.45359237 kg. exactly. 2. Specifically, a unit of measurement of the thrust or force of a reaction engine representing the weight the engine can move, as an engine with 100,000 pounds of thrust. 3. The force exerted on a one pound mass by the standard acceleration of gravity." That really shouldn't come as any surprise to you, does it, at this stage of the game? I believe I had stated the same thing in so many words, earlier. Interestingly, they also define poundal, pound mass and pound weight. No mention of pound force. Evidently, that would be redundant. ;-) Have you figured out yet what those poundals are, and how they are used? Were you not able to ascertain that from my earlier post where I referenced the definition in Halliday and Resnick? One thing about the CRC Handbook (which edition?) is that they include stuff put in there over a period of many years, most of it undated. Those "pounds weight" are an obsolete term for what are now called pounds force. So which units of weight do you think we're supposed to use now? 73, Jim AC6XG |
On 30 Sep 2003 18:36:50 GMT, (Tdonaly) wrote:
Cecil wrote, Gene Nygaard wrote: You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. Here's an interesting quote from _University_Physics_ by Young and Freedman: "On the moon, a stone would be just as hard to throw horizontally, but it would be easier to lift." It also says weight is a vector and mass is a scalar. -- 73, Cecil http://www.qsl.net/w5dxp You better watch out, Cecil, Gene is liable to write a scathing indictment of your intelligence, integrity, and job fitness, for quoting that. By the way, I don't know why I would. I agree with the quoted part. Of course, though the stone is just as hard to throw, it will likely go farther before it falls to the ground. Would you say that a boat is heavy because it is hard to push away from the dock? What is the relevant factor here--that it is pressing down with a force due to gravity of 9000 pounds force? Or that it has a mass of 9000 pounds? What is the metric equivalent of a ton used for the weight of a U.S. Navy ship? For example, the tanker USNS Henry J. Kaiser is 27,561 tons deadweight. How much is that is SI units? Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Tue, 30 Sep 2003 14:21:14 -0700, Jim Kelley
wrote: Gene Nygaard wrote: It doesn't cost you any more to pay attention. Repeat to yourself until you understand it: Weight is an AMBIGUOUS word. IT HAS SEVERAL DIFFERENT MEANINGS. What cause have I given you to write to me in such a manner? The one you cite from the Chemical Rubber Company is, of course, one of those several definitions. If it always meant the same as mass in physics jargon, I wouldn't have to point out to you that this is an ambiguous word, would I? This is the first you've mentioned anything about it being ambiguous. You just haven't been paying attention. Until now, you've just been belligerent and accusational about it. Didn't you read the message you responded to, especially what immediately followed the sentence you quoted? Didn't you see what NIST and ASTM have to say about this? Look at it again, and read it slowly this time I'm commenting on what you said, Gene. I have no comment on what NIST had to say. 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 Learn to evaluate your sources, also. Those sources are more credible than any CRC Handbook on this subject. You need to learn how to attribute yours. I didn't write that. :-) There isn't any standard way of handling this, as far as I know. I've seen it done several different ways, none of them completely satisfactory. So I'm open to suggestions, if you can tell us how you think it should be done. Next time I'll mark the end of the quote from an earlier message, as well as the beginning--would that satisfy you? Your definition of weight is not the proper one to use for your body weight in the doctor's office or the gym. I don't write definitions. But the ones I have cited are no less accurate in the doctors office than the physics lab. They are incorrect in the doctor's office, and even more incorrect in the supermarket or the jewelry store. Like I said, you don't have to call the quantities used there "weight"--but if you do call them weight, use the definition which is correct in that context. Don't misinterpret what is being used there. You can, of course, choose not to call this quantity "weight." You can call it mass instead, if you want to. As I recall, the argument was about whether to call it a mass or a force. You recall incorrectly. It's generally accepted that weight is a force. I've shown in this thread from the experts in the field, including NIST (the U.S. national standards agency) and ASTM (an industry standards agency) and NPL (the U.K. national standards agency) and the Canadian Standard for Metric Practice, that this is false. All of these sources and many others tell you that weight is an ambiguous word, with several different meanings. Problems can arise when someone claims a mass is a force and vice versa. I agree. Furthermore, it is not an acceptable option to misinterpret what they are saying, and to misapply an inappropriate definition of weight. It is possible that you are doing some of the misinterpreting. You could, of course, argue that we should all change to your usage. Many people already have, obviously. Not very many, surprisingly. It is much more common to find people claiming, erroneously, that there is some error in that usage. Reflecting the apparent dichotomy, the CRC defines the pound both ways: "1. A unit of mass equal in the U.S. to 0.45359237 kg. exactly. 2. Specifically, a unit of measurement of the thrust or force of a reaction engine representing the weight the engine can move, as an engine with 100,000 pounds of thrust. 3. The force exerted on a one pound mass by the standard acceleration of gravity." That really shouldn't come as any surprise to you, does it, at this stage of the game? I believe I had stated the same thing in so many words, earlier. Interestingly, they also define poundal, pound mass and pound weight. No mention of pound force. Evidently, that would be redundant. ;-) Have you figured out yet what those poundals are, and how they are used? Were you not able to ascertain that from my earlier post where I referenced the definition in Halliday and Resnick? No, I couldn't tell one way or the other from your mere statement that the poundal was idenitified in that appendix as a unit of force whether or not you know anything about the system in which they are used. Like slugs, poundals only exist in one limited purpose system of mechanical units, mostly used to simplify calculations. Do you understand how these systems are used, and the difference between them. The part you snipped (the second sentence in the last paragraph of mine quited above) makes it clearer that this is what I was asking about. So tell me now, what is the base unit of mass in the system in which poundals are the derived unit of force? Do you understand that yet? I still don't know. Gene Nygaard http://ourworld.compuserve.com/homepages/Gene_Nygaard/ |
On Tue, 30 Sep 2003 14:17:53 GMT, Gene Nygaard
wrote: On Mon, 29 Sep 2003 23:38:14 -0500 (CDT), (Richard Harrison) wrote: Gene Nygaard wrote: "Look in the textbooks you used, and see if the authors have any footnotes citing the authority for whatever definition they use. My Random House American College Dictionary (circa 1950) says: "kilogram, n. Metric System. a unit of mass and weight, equal to 1000 grams and equivalent to 2.2046 pounds avoirdupois. For pounds, the same dictionary says: "Pound. 1. a unit of weight and of mass, varying in different periods and countries. Pounds and kilograms are different units for the same things, force and weight. Still haven't figured out that your claims that both kilograms and pounds are names of both a unit of mass and a unit of force is at odds with what Dave Shrader and Richard Clark have been telling us, have you? Okay people.... before this thread goes any further wrong than it already has.... Kilograms (base unit of measurement, the gram) are units of MASS. This is a measure of the amount matter in an object... Pounds are a unit of force, a measurement of the gravitational attraction a body has relative to another, reference, body. A 2 kilogram object will have the same mass on the earth as it does on the moon. A 60 pound object on the earth will have a weight of 10 pounds on the moon. If you kiddies are going to argue physics, you really SHOULD get your terms straight. God, pseudo-intellectuals really do begin to wear thin quite quickly... Raymond Sirois KU2S SysOp: The Lost Chord BBS 607-733-5745 telnet://thelostchord.dns2go.com:6000 |
Gene Nygaard wrote:
"Those "pounds weight are an obsolete term for what are now called pounds force." Spoken like a weight-loss promoter. Good mathematics becomes obsolete very slowly. Archimedes found the approximate value of pi in the 3rd century before Christ. Archimedes inscribed the largest regular polygon ithat would fit inside a circle. Next he drew outside the circle a similar regular polygon touching the circle on all sides and having its sides parallel to the polygon sides inside the circle. Then he increased the number of sides of his polygons until they totaled 96. He decided a 96-side, equal-sided, figure was close enough to a circle for practical purposes. He also knew that a real circle would have a circumference somewhere between the circumferences of his inside and outside polygons. Also, the circumferences of his inside and outside figures were very nearly the same anyway. The tape measure must not have yet been invented, so Archimedes must have measured the sides of his figures with a straight ruler. He used the sums of the polygon sides to arrive at the circumference of his figures. From these constructions and measurements, Archimedes arrived at a figure of 3.1416 for the ratio of circumference to the diameter of a circle (pi). That`s still close enough for most purposes to this very day. There was a PBS special here today on "The Method" one of the books written by Archimedes, a copy of which was recently sold at auction for 2 million dollars. Archimedes was slain in his laboratory by a Roman soldier in spite of orders that he be taken alive and transported to Rome. He was the top Greek war machine designer. Best regards, Richad Harrison, KB5WZI |
Richard Harrison wrote:
There was a PBS special here today on "The Method" one of the books written by Archimedes, a copy of which was recently sold at auction for 2 million dollars. Very interesting program. Archimedes apparently developed an elementary calculus involving infinity 300 years before Jesus was born. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Gene Nygaard wrote:
"What is the relevant factor here -- that it is pressing down with a force due to gravity of 9000 pounds due to gravity of 9000 pounds force? Or that it has a mass of 9000 pounds? The tonnage of a ship is the weight of the water it displaces. The force pressing down (normal force) in mechanical problems is significant when friction is involved. Force equals mass time acceleration. So, the mass opposes and increases the force required to get an object moving, or slowed, for that matter. That includes a ship. It has inertia and requires force to change its velocity. Drag is imposed on the submerged portion of the hull, especially when coated with barnacles. I shipped out of Long Beach in WW-2 on the LSM 472. I returned to San Francisco on the LSM 94. I was transferred to the LST 604 to take it up river to Stockton to be decomissioned and scrapped. While at the ship yard there I witnessed a curious sight. A large merchant vessel was moved from one berth to another using a small boat with an outboard motor as the tow boat. River current in the basin was almost nil, yet it took several hours to move that large ship with the power of only an outboard motor. It worked! There must have been nothing more powerful available and there must have been no rush to get the berth swap made. Point is that it is likely that neither mass nor weight is as important as current in many situations. How soon you can get up to speed depends a lot on mass as Newton predicts. That motorboat would have done its thing much more quickly with a waterskier in tow than it did with a big merchant ship in tow. Best regards, Richard Harrison, KB5WZI |
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