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JimTitt
May 27, 2010, 7:53 PM
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Nice thread, takes me back to my younger days when we had to do physics and mechanics in fps.
"Usage of the unqualified term pound reflects the historical conflation of mass and weight resulting from the near uniformity of gravity on Earth. This accounts for the modern distinguishing terms pound-mass and pound-force."
I´m sticking to kN and litres (of beer)!
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rgold
May 27, 2010, 8:11 PM
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Jim, you're lucky. I had to use kilocubits per month.
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ptlong
May 27, 2010, 8:13 PM
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I like the British units. You order a pint and you get an extra four ounces!
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hafilax
May 27, 2010, 8:16 PM
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For some reason pound feet always gets me singing We Will Rock You.
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jt512
May 27, 2010, 8:26 PM
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chadnsc wrote: Yes, yes it does. Now will all you internet physicist please stop as I feel like I'm listening to a group of high school geeks arguing about which version of Star Trek is better.
Next Generation. What's there to discuss?
Jay
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chadnsc
May 27, 2010, 8:31 PM
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jt512 wrote: chadnsc wrote: Yes, yes it does. Now will all you internet physicist please stop as I feel like I'm listening to a group of high school geeks arguing about which version of Star Trek is better. . What's there to discuss? Jay
Aye Aye Captin'!
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jt512
May 27, 2010, 8:38 PM
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rgold wrote: Thanks. If we can't force it to end, perhaps we can at least accelerate its demise?
Is there some way we can prevent threads like this in the future? An ounce of prevention is worth a pound of cure.
Jay
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hafilax
May 27, 2010, 8:38 PM
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jt512 wrote: chadnsc wrote: Yes, yes it does. Now will all you internet physicist please stop as I feel like I'm listening to a group of high school geeks arguing about which version of Star Trek is better. . What's there to discuss? Jay
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chadnsc
May 27, 2010, 8:53 PM
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hafilax wrote: jt512 wrote: chadnsc wrote: Yes, yes it does. Now will all you internet physicist please stop as I feel like I'm listening to a group of high school geeks arguing about which version of Star Trek is better. . What's there to discuss? Jay Now who's embarrassing himself?
WWWWHHAAAAAATTTT?
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drector
May 27, 2010, 9:02 PM
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hafilax wrote: jt512 wrote: chadnsc wrote: Yes, yes it does. Now will all you internet physicist please stop as I feel like I'm listening to a group of high school geeks arguing about which version of Star Trek is better. . What's there to discuss? Jay Now who's embarrassing himself?
Not Jay.
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adatesman
May 27, 2010, 9:04 PM
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gmggg
May 27, 2010, 9:18 PM
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adatesman wrote: jt512 wrote: adatesman wrote: jt512 wrote: In contrast to your assertion back on page one, you can even buy them at Home Depot. Jay Ridiculous because it proves you wrong on something? At no point did I say they weren't available; feel free to go back and check. I only said that they're not common (implication being here in the US, since that's where we both are) and not likely to be available at the local home center or used (or even heard of) by the average climber pulling the tape measure out of their junk drawer when looking to measure some rope. My guess is that you know as many people as I do who have decimal inch tape measures (read: 0). That said, I have a bunch of steel rules that are marked in fractional inch, decimal inch and centimeters, but damned if I was going to try and measure a rope length with them. BTW, your link goes to Home Depot CANADA, where they are more likely to sell Metric tape measures. Does it really bother you this much to be wrong about something? I keep pushing and pushing and you keep doing everything you can to avoid admitting you just may have made a mistake, even when confronted with concrete evidence of it. Which brings us back to the main thing I've heard from you in this thread: Jay is never wrong. Sure, you've had some valid points along the way, but the main thing that comes across (to me at least) is that you don't like being questioned, or god forbid found in error. I guess your condescending attitude towards others on RC has gotten under my skin lately and I figured I'd see how much of your time I could waste. Frankly I'm surprised you spent this much time on it. TTFN, I'm going to bed. I may check in again at 3 when the baby wakes up, but she's been sleeping good of late (fingers crossed!). -a. Oy, Aric. Nobody gives a damn about tape measures. And your definition of "pushing" apparently means making factual mistake after factual mistake, and then blaming me for not admitting I'm wrong. Do what rgold suggested 2 pages back: give it a rest. You're only embarrassing yourself. Jay Jesus Jay, is it really that hard for you to admit that the tape measure in your desk is feet and inches, and therefore your contention that doing the calculations in English units is no more difficult than doing it in Metric is in fact wrong?
.jpg)
I think you're breaking this record on purpose.
Oh. And Jay's original assertion is correct, unless you're needing to convert between units the system you use does not add complication.
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jt512
May 27, 2010, 9:22 PM
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adatesman wrote: jt512 wrote: adatesman wrote: jt512 wrote: In contrast to your assertion back on page one, you can even buy them at Home Depot. Jay Ridiculous because it proves you wrong on something? At no point did I say they weren't available; feel free to go back and check. I only said that they're not common (implication being here in the US, since that's where we both are) and not likely to be available at the local home center or used (or even heard of) by the average climber pulling the tape measure out of their junk drawer when looking to measure some rope. My guess is that you know as many people as I do who have decimal inch tape measures (read: 0). That said, I have a bunch of steel rules that are marked in fractional inch, decimal inch and centimeters, but damned if I was going to try and measure a rope length with them. BTW, your link goes to Home Depot CANADA, where they are more likely to sell Metric tape measures. Does it really bother you this much to be wrong about something? I keep pushing and pushing and you keep doing everything you can to avoid admitting you just may have made a mistake, even when confronted with concrete evidence of it. Which brings us back to the main thing I've heard from you in this thread: Jay is never wrong. Sure, you've had some valid points along the way, but the main thing that comes across (to me at least) is that you don't like being questioned, or god forbid found in error. I guess your condescending attitude towards others on RC has gotten under my skin lately and I figured I'd see how much of your time I could waste. Frankly I'm surprised you spent this much time on it. TTFN, I'm going to bed. I may check in again at 3 when the baby wakes up, but she's been sleeping good of late (fingers crossed!). -a. Oy, Aric. Nobody gives a damn about tape measures. And your definition of "pushing" apparently means making factual mistake after factual mistake, and then blaming me for not admitting I'm wrong. Do what rgold suggested 2 pages back: give it a rest. You're only embarrassing yourself. Jay Jesus Jay, is it really that hard for you to admit that the tape measure in your desk is feet and inches, and therefore your contention that doing the calculations in English units is no more difficult than doing it in Metric is in fact wrong?
Aric, doing calculations in meters is easier than doing calculations using feet and inches. Will you please now shut the fuck up.
youtube.com
Jay
(This post was edited by jt512 on May 27, 2010, 9:28 PM)
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swoopee
May 27, 2010, 9:24 PM
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jt512 wrote: swoopee wrote: jt512 wrote: swoopee wrote: I thought slug was mass and pound was force. But anyway I thought the discussion was about kilonewtons, particularly as they apply in climbing. So here is my opinion, meaning most probably wrong and therefore worthless, anytime I fall I expect the force on the tie in points of my harness to be somewhere in the neighborhood of 0.85-0.90kN assuming that the fall is not so hard as to stretch the rope to max elongation before slowing my velocity to somewhere in the vicinity of 0. So that said, I have to guess that the force at the other end of the rope is close to the same, maybe a bit lower due to friction and the force on the anchor is very close to the combined forces. In other words, assuming that the belayer is not tied in, or at least can be pulled upward a few feet, the force on the top anchor is roughly equal to, or slightly greater than the weight of the climber + the weight of the belayer. So, while I know this is probably all wrong... Not "probably." "Completely" might describe it. In reply to: ...it works for me... "It" does not "work for" you. "It" is completely wrong. It just doesn't matter, because the gear you're using is strong enough to hold the actual impact forces. If, you were to design an anchor based on "it," you'd quickly discover—well, your survivors would, anyway—how well "it" "works for" you. Jay Just reread your post, and actually that was my point. We are actually in agreement here, dang it. Although we may be in agreement that, since the gear is good enough, your underestimation of the impact forces doesn't matter, we are not in agreement about the magnitude of the impact forces. You believe that the force on the anchor in a typical lead fall is just over two times body weight. However, it can easily be shown that the force on the anchor in a top rope "fall" with no slack in the rope will be about 3-1/3 times body weight. Thus, you believe that a typical lead fall will produce less force on the anchor than the mildest possible toprope "fall." Jay
Okey you know, I'm not saying that you're wrong but I gotta see this. But yes, you are correct in that I do not believe that a "typical" lead fall necessarily loads the anchor much more than a "typical" toprope fall. BTW, I refuse to even attempt to define typical in either case. 
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MS1
May 27, 2010, 9:28 PM
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adatesman wrote: jt512 wrote: adatesman wrote: jt512 wrote: In contrast to your assertion back on page one, you can even buy them at Home Depot. Jay Ridiculous because it proves you wrong on something? At no point did I say they weren't available; feel free to go back and check. I only said that they're not common (implication being here in the US, since that's where we both are) and not likely to be available at the local home center or used (or even heard of) by the average climber pulling the tape measure out of their junk drawer when looking to measure some rope. My guess is that you know as many people as I do who have decimal inch tape measures (read: 0). That said, I have a bunch of steel rules that are marked in fractional inch, decimal inch and centimeters, but damned if I was going to try and measure a rope length with them. BTW, your link goes to Home Depot CANADA, where they are more likely to sell Metric tape measures. Does it really bother you this much to be wrong about something? I keep pushing and pushing and you keep doing everything you can to avoid admitting you just may have made a mistake, even when confronted with concrete evidence of it. Which brings us back to the main thing I've heard from you in this thread: Jay is never wrong. Sure, you've had some valid points along the way, but the main thing that comes across (to me at least) is that you don't like being questioned, or god forbid found in error. I guess your condescending attitude towards others on RC has gotten under my skin lately and I figured I'd see how much of your time I could waste. Frankly I'm surprised you spent this much time on it. TTFN, I'm going to bed. I may check in again at 3 when the baby wakes up, but she's been sleeping good of late (fingers crossed!). -a. Oy, Aric. Nobody gives a damn about tape measures. And your definition of "pushing" apparently means making factual mistake after factual mistake, and then blaming me for not admitting I'm wrong. Do what rgold suggested 2 pages back: give it a rest. You're only embarrassing yourself. Jay Jesus Jay, is it really that hard for you to admit that the tape measure in your desk is feet and inches, and therefore your contention that doing the calculations in English units is no more difficult than doing it in Metric is in fact wrong?
Dude, is it so hard to admit that probably no one, in the entire history of climbing, has whipped out a tape measure when trying to figure out a fall factor? Seriously, no one estimates more precisely than feet (or maybe half a foot if it's a very short fall). I can't think of a single time that someone has asked a fall force question involving inches rather than just feet.
So you are coming across as kind of crazy. I normally enjoy your posts so I'm telling you this as a kind of intervention. Let the tape measure thing rest!
(Unless, of course, this whole thing is a troll designed to help a thread that only needed a one sentence response run to 10 pages. In which case, kudos.)
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jt512
May 27, 2010, 9:41 PM
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swoopee wrote: jt512 wrote: swoopee wrote: jt512 wrote: swoopee wrote: I thought slug was mass and pound was force. But anyway I thought the discussion was about kilonewtons, particularly as they apply in climbing. So here is my opinion, meaning most probably wrong and therefore worthless, anytime I fall I expect the force on the tie in points of my harness to be somewhere in the neighborhood of 0.85-0.90kN assuming that the fall is not so hard as to stretch the rope to max elongation before slowing my velocity to somewhere in the vicinity of 0. So that said, I have to guess that the force at the other end of the rope is close to the same, maybe a bit lower due to friction and the force on the anchor is very close to the combined forces. In other words, assuming that the belayer is not tied in, or at least can be pulled upward a few feet, the force on the top anchor is roughly equal to, or slightly greater than the weight of the climber + the weight of the belayer. So, while I know this is probably all wrong... Not "probably." "Completely" might describe it. In reply to: ...it works for me... "It" does not "work for" you. "It" is completely wrong. It just doesn't matter, because the gear you're using is strong enough to hold the actual impact forces. If, you were to design an anchor based on "it," you'd quickly discover—well, your survivors would, anyway—how well "it" "works for" you. Jay Just reread your post, and actually that was my point. We are actually in agreement here, dang it. Although we may be in agreement that, since the gear is good enough, your underestimation of the impact forces doesn't matter, we are not in agreement about the magnitude of the impact forces. You believe that the force on the anchor in a typical lead fall is just over two times body weight. However, it can easily be shown that the force on the anchor in a top rope "fall" with no slack in the rope will be about 3-1/3 times body weight. Thus, you believe that a typical lead fall will produce less force on the anchor than the mildest possible toprope "fall." Jay Okey you know, I'm not saying that you're wrong but I gotta see this.
Go here. A top rope fall with no slack in the rope has a fall factor of 0. So enter "0" for fall factor, and whatever you want to for the other variables. Click "calculate." Convert the force on the anchor from kN to lbs, which we are all now experts at doing. Dividing the result by the weight you entered gives 3.333....
Jay
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kennoyce
May 27, 2010, 10:53 PM
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I certainly concede that in all of the definitions you have provided, a pound is a measurement of mass.
Just for your future knowledge. Here in the USA where we use pounds, what is taught in school and what is used by the general population is the foot pound system or whatever the system is called where a pound is a measurement of force and a slug is the measurement of mass.
This may not be what the official stance by the government is, but it is what is used. If the government had any brains in them they would just due away with the whole crazy system and switch over to SI, but that will never happen.
So basically I'm saying that you are correct by the definitions given by the government, but they are not the generally accepted or the generally used definitions.
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patto
May 27, 2010, 11:59 PM
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Thank you edm and ptlong for the support and for reading the links and acknowledging the edvidence.
redlude97 wrote: ptlong wrote: My impression is that the average man on the street doesn't make the distinction. Thats exactly the point. If the average man uses the term weight, then it is common to assume they are referring to pounds in force, because by the very definition, weight is a force term
The average man in doesn't make the disctinction between mass and weight. I think we all understand this basing your argument upon the use of the term by the average man is clutching at straws.
Somebody asks my body weight and I'll tell them 70kg. So would anybody in the country where im from. What the average man thinks isn't that relevent because it is quite clear mass and weight are used interchangably in everyday life.
Further to add to the confusion, not that not all 'scales' measure weight. Traditional balance scales measure mass and thus will give you the same reading on moon as on the earth. A balance scale using pounds actually gives you the measurment in pounds mass.
edm wrote: I find this interesting because American schools definitely teach that a pound is a unit of force,  Intelligent design debate anybody?
I find it all quite bizarre. In trade, commerce and industry standards are important. If I order 1000kg of wheat I want 1000kg of wheat I don't want 9800kN of wheat. While the distinction is academic because on earth mass(kg-lb)='weight'(kg-lb) it still makes sense that we require quantities in MASS not weight. (even if a weight measurement is used as a proxy for mass)
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redlude97
May 28, 2010, 12:24 AM
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patto wrote: Thank you edm and ptlong for the support and for reading the links and acknowledging the edvidence. redlude97 wrote: ptlong wrote: My impression is that the average man on the street doesn't make the distinction. Thats exactly the point. If the average man uses the term weight, then it is common to assume they are referring to pounds in force, because by the very definition, weight is a force term The average man in doesn't make the disctinction between mass and weight. I think we all understand this basing your argument upon the use of the term by the average man is clutching at straws. Somebody asks my body weight and I'll tell them 70kg. So would anybody in the country where im from. What the average man thinks isn't that relevent because it is quite clear mass and weight are used interchangably in everyday life. Further to add to the confusion, not that not all 'scales' measure weight. Traditional balance scales measure mass and thus will give you the same reading on moon as on the earth. A balance scale using pounds actually gives you the measurment in pounds mass. edm wrote: I find this interesting because American schools definitely teach that a pound is a unit of force, Personally I have greater concerns about the state of US schools science teaching than this issue. Intelligent design debate anybody? I find it all quite bizarre. In trade, commerce and industry standards are important. If I order 1000kg of wheat I want 1000kg of wheat I don't want 9800kN of wheat. While the distinction is academic because on earth mass(kg-lb)='weight'(kg-lb) it still makes sense that we require quantities in MASS not weight. (even if a weight measurement is used as a proxy for mass)
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ptlong
May 28, 2010, 12:42 AM
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patto wrote: I think we all understand this basing [the] argument upon the use of the term by the average man is clutching at straws.
Or just a different argument. You're saying: here's what NIST says, and they're saying here's what most people think, or, here's what we were taught in school.
What exactly was the original question? ha ha ha
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curt
May 28, 2010, 12:45 AM
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rgold wrote: In spite of the massive size of this thread, people keep pounding the same points over and over again. Pool old Newton would have succumbed to a headache days ago. Is there no way to force them to stop? If only we could just send out a cease-and-desist tele gram! I think that about covers it...
Personally, I'm about to slug somebody.
Curt
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jt512
May 28, 2010, 12:47 AM
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ptlong wrote: What exactly was the original question?
What is a kilonewton?
Edit: Actually, looking at the thread title, the OP asked for a "discussion of [the] meaning of 'kilonewtons'." Well, he got one!
Jay
(This post was edited by jt512 on May 28, 2010, 12:49 AM)
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ptlong
May 28, 2010, 12:48 AM
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redlude97 wrote: Wrong. A balance scale still measures weight. It technically compares torques, but that is a whole other topic. The only reason a balance scale works is because of the force exerted on the masses from the gravitation pull of the earth. Take scale into space and it doesn't matter how much mass you put on one end.
It's true a balance scale will not work unless in a non-inertial frame (or a gravitational equivalent), but it is most certainly comparing two masses, hence measuring the unknown one.
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patto
May 28, 2010, 12:55 AM
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redlude97 wrote: Wrong. A balance scale still measures weight. It technically compares torques, but that is a whole other topic. The only reason a balance scale works is because of the force exerted on the masses from the gravitation pull of the earth. Take scale into space and it doesn't matter how much mass you put on one end.
Arrrg! I knew somebody would try to disagree with me here.
Sure it compares torque, torque produced by an objects weight. And sure it needs non negligable gravity to work. However the answer it outputs is the fixed mass of the object being measured. If you wanted to do the engineering calculations you would see that 'g' gravitational accelleration drops out of the calculation, leaving only 'm' mass.
Your argument is akin to saying runners stop watch doesn't measure time it measures the number of vibrations of a quartz crystal during the run.
http://en.wikipedia.org/wiki/Weighing_scale
In reply to: The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented.
If you choose to continue to argue this fine. I won't.
EDIT:
Further to the previous argument. There is indeed recognition of the important of measuring MASS accurately in US commerce and not of weight.
In reply to: Testing and certification ...Because gravity varies by over 0.5% over the surface of the earth, the distinction between force due to gravity and mass is relevant for accurate calibration of scales for commercial purposes. Usually the goal is to measure the mass of the sample rather than its force due to gravity at that particular location. Traditional mechanical balance-beam scales intrinsically measured mass. But ordinary electronic scales intrinsically measure the gravitational force between the sample and the earth, i.e. the weight of the sample, which varies with location. So such a scale has to be re-calibrated after installation, for that specific location, in order to obtain an accurate indication of mass.
Anybody who has ever calibrated a scale would know that an objecy of fixed MASS is used not an object of fixed WEIGHT.
ALSO:
ptlong wrote: Or just a different argument. You're saying: here's what NIST says, and they're saying here's what most people think, or, here's what we were taught in school.
I would also argue that when people go buy 2lb of steak what people really are wanting is 2lb mass not weight. Furthermore what is legally required to give is 2lb mass not weight. Butcher scales are calibrated to a fixed MASS not a fixed weight. It is quite clear that they 'measure' weight thought the answer the give is a calibrated reading of MASS. Their measurement of pounds-force is inaccurate unless gravity at the location is precisely standard gravity.
(But I'm sure somebody will argue with this paragraph.)
(This post was edited by patto on May 28, 2010, 1:14 AM)
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