syntax252 Posted February 20, 2005 Author Share Posted February 20, 2005 INow Centrifugal force is something of an illusion. Consider Newton's first law of motion (Though Rene Descartes actually postulated the principle first.) - the velocity of a body remains constant unless acted upon by a force. Now velocity is not speed' date=' but speed in a constant direction. In other words, unless we interfere with it a body will remain at rest or moving in the same direction at the same speed for ever. This property of carrying on regardless is called inertia. In the example of the spin dryer the clothes want to carry on in a straight line, but are restrained by the walls of the dryer. The water isn't. It is simply continuing in a straight line. This creates the [i']appearance [/i]of a force throwing the water off and trying to throw the clothes off, but in both cases it is simply inertia. Hope that makes some kind of sense. Just for the hell of it I asked Merriam Webster and here is what he said: Main Entry: centrifugal force Function: noun 1 : the force that tends to impel a thing or parts of a thing outward from a center of rotation 2 : the force that an object moving along a circular path exerts on the body constraining the object and that acts outwardly away from the center of rotation <a stone whirled on a string exerts centrifugal force on the string> Now, I know that sometimes scientific terms are not entirely in line with terms found in dictionaties, but I think that this at least, explains why we (lay people) call centrifugal force centrifugal force. While I was at it, I looked for "centripital force" and this is what I got: The word you've entered isn't in the dictionary. Click on a spelling suggestion below or try again using the search box to the right. Suggestions for main entry: centrifugal force: Not trying to get a big fight started, but why doesn't MW have a file on centripital force? Link to comment Share on other sites More sharing options...
5614 Posted February 20, 2005 Share Posted February 20, 2005 Not trying to get a big fight started, but why doesn't MW have a file on centripital force? This is like the whole what's you weight in kilogram thing! Some of you may know that weight is measured in newtons, mass is measured in kilograms and grams... however if you walk up to someone and ask them what they weigh you'll get an answer in KG (or stones!)... this is technically incorrect though. Simiarly the difference between centrifugal and centripetal is not widely known, however places such as a science forums should get things like this right... hence this thread! Link to comment Share on other sites More sharing options...
us.2u Posted February 20, 2005 Share Posted February 20, 2005 The way I see this; is really everyone is agreeing with each other; but getting too nit- picky concentrate on Ophiolites post... forgive the pun but weigh up all his maths & realise there is no argument here, but different angles on the way one views Link to comment Share on other sites More sharing options...
swansont Posted February 21, 2005 Share Posted February 21, 2005 Just for the hell of it I asked Merriam Webster and here is what he said:Main Entry: centrifugal force Function: noun 1 : the force that tends to impel a thing or parts of a thing outward from a center of rotation 2 : the force that an object moving along a circular path exerts on the body constraining the object and that acts outwardly away from the center of rotation <a stone whirled on a string exerts centrifugal force on the string> Now' date=' I know that sometimes scientific terms are not entirely in line with terms found in dictionaties, but I think that this at least, explains why we (lay people) call centrifugal force centrifugal force. [/quote'] Note that the centrifugal force is exerted by the object (stone on string) while an object's acceleration is dictated by the forces acting on the object. In an inertial frame, there are no centrifugal forces felt by anything - an object moving in a circle is not pushed outwards. It is pulled inwards. Definition #1 is coprolitic. (it's utter BS, and old BS at that) Oh, BTW: "I asked Merriam Webster and here is what he said" It's not a "he." Merriam refers to brothers George and Charles Merriam, and Webster is Noah Webster. It's a company. And the people working there apparently aren't physicists nor worried about scientific definitions. Link to comment Share on other sites More sharing options...
syntax252 Posted February 21, 2005 Author Share Posted February 21, 2005 Note that the centrifugal force is exerted by the object (stone on string) while an object's acceleration is dictated by the forces acting on the object. In an inertial frame' date=' there are no centrifugal forces felt by anything - an object moving in a circle is [b']not[/b] pushed outwards. It is pulled inwards. Definition #1 is coprolitic. (it's utter BS, and old BS at that) Oh, BTW: "I asked Merriam Webster and here is what he said" It's not a "he." Merriam refers to brothers George and Charles Merriam, and Webster is Noah Webster. It's a company. And the people working there apparently aren't physicists nor worried about scientific definitions. Well OK, if you say so. I will tell the brothers Merriam how full of shit you said they are, it is too late for Webster--right? Anyway, what was that other word you used? centripital force? Any idea why they didn't have any info on it? Link to comment Share on other sites More sharing options...
Sayonara Posted February 21, 2005 Share Posted February 21, 2005 The Merriam-Webster dictionary is full of shit. It's not a matter of one physicist's opinion. They won't have anything on centripetal force for the same reason they don't have a definition for every word we use - because the book is not exhaustive, and as has been pointed out a million times, it is not a technical reference for any discipline. Link to comment Share on other sites More sharing options...
syntax252 Posted February 21, 2005 Author Share Posted February 21, 2005 Maybe yes, and maybe no...... From the merriam brothers: Main Entry: centripetal force Function: noun : the force that is necessary to keep an object moving in a circular path and that is directed inward toward the center of rotation <a string on the end of which a stone is whirled about exerts centripetal force on the stone> It turns out that it is centripEtal force and not centripItal force. So maybe they are not as full of shit as they are alleged to be? Link to comment Share on other sites More sharing options...
Sayonara Posted February 21, 2005 Share Posted February 21, 2005 I don't really see how them having a workable definition for centripetal force, as opposed to having no definition for it, changes the degree to which their shitty definitions are shitty. Link to comment Share on other sites More sharing options...
YT2095 Posted February 21, 2005 Share Posted February 21, 2005 you have to admire their spelling prowess though Link to comment Share on other sites More sharing options...
syntax252 Posted February 21, 2005 Author Share Posted February 21, 2005 I don't really see how them having a workable definition for centripetal force, as opposed to having no definition for it, changes the degree to which their shitty definitions are shitty. Well, is their definition of centripetal force accurate? Link to comment Share on other sites More sharing options...
syntax252 Posted February 21, 2005 Author Share Posted February 21, 2005 you have to admire their spelling prowess though And a lot better than mine. Link to comment Share on other sites More sharing options...
Sayonara Posted February 22, 2005 Share Posted February 22, 2005 Well, is their definition of centripetal force accurate? Ask the physicist. Link to comment Share on other sites More sharing options...
swansont Posted February 22, 2005 Share Posted February 22, 2005 Well, is their definition of centripetal force accurate? Yes. But they also define accelerate as "to move faster" which is incorrect from a technical perspective. Sayo's sig line is still spot-on, and applies to M-W. Link to comment Share on other sites More sharing options...
Rasori Posted February 22, 2005 Share Posted February 22, 2005 Centrifugal force is just an 'illusion' created by inertia/momentum, is it not? I have heard that it doesn't exist, but things like it do exist, hence the term illusion. Dunno, that's just my take on the matter. Link to comment Share on other sites More sharing options...
syntax252 Posted February 22, 2005 Author Share Posted February 22, 2005 Yes. But they also define accelerate as "to move faster" which is incorrect from a technical perspective. Sayo's sig line is still spot-on' date=' and applies to M-W.[/quote'] If their difinition was accurate for the term that we were discussing, isn't it a "strawman" argument to point to some other definition that a physicist might find wanting? Link to comment Share on other sites More sharing options...
losfomot Posted February 22, 2005 Share Posted February 22, 2005 If their difinition was accurate for the term that we were discussing, isn't it a "strawman" argument to point to some other definition that a physicist might find wanting? Actually, Swansont was arguing the definition of centrifugal force (which was the term in discussion). The CENTRIPETAL force definition came later and, in this particular case, was a correct definition (which Swansont agreed on). The point of all the dictionary guffaw was simply to let you know that the dictionary is NOT always right, and should NOT be used as a technical resource (as you used it). It really seems like YOU are trying to create an argument out of nothing. Link to comment Share on other sites More sharing options...
syntax252 Posted February 22, 2005 Author Share Posted February 22, 2005 Actually' date=' Swansont was arguing the definition of centrifugal force (which was the term in discussion). The CENTRIPETAL force definition came later and, in this particular case, was a correct definition (which Swansont agreed on). The point of all the dictionary guffaw was simply to let you know that the dictionary is NOT always right, and should NOT be used as a technical resource (as you used it). It really seems like YOU are trying to create an argument out of nothing.[/quote'] Actually, if you will go back abd read my post carefully you will find that I acknowledge that very thing when I first introduced Merriam Webster into this discussion........ Added later: That was post #26 if you would care to look it up. Link to comment Share on other sites More sharing options...
swansont Posted February 23, 2005 Share Posted February 23, 2005 If their difinition was accurate for the term that we were discussing, isn't it a "strawman" argument to point to some other definition that a physicist might find wanting? No. Why would you think it was? Link to comment Share on other sites More sharing options...
syntax252 Posted February 23, 2005 Author Share Posted February 23, 2005 No. Why would you think it was? Because it doen not speak to the issue under discussion? Link to comment Share on other sites More sharing options...
swansont Posted February 23, 2005 Share Posted February 23, 2005 Because it doen not speak to the issue under discussion? The discussion of whether a lay dictionary is a technical resource? How is it not relevant? Link to comment Share on other sites More sharing options...
Ophiolite Posted February 23, 2005 Share Posted February 23, 2005 I just noticed what this thread was meant to be about.. Syntax, an almost identical question was dealt with more fully here: http://www.scienceforums.net/forums/showthread.php?t=8263&highlight=galaxy+velocity+relative Link to comment Share on other sites More sharing options...
syntax252 Posted February 23, 2005 Author Share Posted February 23, 2005 The discussion of whether a lay dictionary is a technical resource? How is it not relevant? It is not relevant because we were discussing the movement of Earth through space and the question about the dictionary sprung from a definition that is accurate. Link to comment Share on other sites More sharing options...
syntax252 Posted February 23, 2005 Author Share Posted February 23, 2005 I just noticed what this thread was meant to be about..Syntax' date=' an almost identical question was dealt with more fully here: http://www.scienceforums.net/forums/showthread.php?t=8263&highlight=galaxy+velocity+relative Actually the questions that I had about Earth's movement were answered some time ago. There seems now to be only the question of whether some force is imparted to the string, or if it is imparted to the stone and whether or not Merriam Webster can be relied upon to know the difference. Link to comment Share on other sites More sharing options...
swansont Posted February 23, 2005 Share Posted February 23, 2005 It is not relevant because we were discussing the movement of Earth through space and the question about the dictionary sprung from a definition that is[/b'] accurate. No, that would be a bit of revisionist history. The current dispute arose from the definition of centrifugal force (post 26), which is not accurate. My response was post 29, and the point was that dictionaries are not guaranteed (or even likely, in some circumstances) to give you accurate technical definitions. In that post (26), you claimed the centripetal force definition did not exist. It was only later that you discovered your typo and posted the definition of that word. (post 32) In post 38 I agreed that their definition of centripetal was correct, but noted that acceleration was incorrect, from a technical standpoint, as support for my argument. I have to ask, was this trip really necessary? Link to comment Share on other sites More sharing options...
syntax252 Posted February 23, 2005 Author Share Posted February 23, 2005 No, that would be a bit of revisionist history. The current dispute arose from the definition of centrifugal force (post 26), which is not accurate. My response was post 29, and the point was that dictionaries are not guaranteed (or even likely, in some circumstances) to give you accurate technical definitions. Well, as I said a few responses ago, I noted at the onset that dictionaries are not always quite in line with scientific terms, so what is the problem? In that post (26), you claimed the centripetal force definition did not exist. It was only later that you discovered your typo and posted the definition of that word. (post 32) No I didn't say that centripetal force did not exist. I asked if there was a reason that MW didn't have a file on it. Nobody offered a reason. In post 38 I agreed that their definition of centripetal was correct, but noted that acceleration was incorrect, from a technical standpoint, as support for my argument. And that is where the strawman argument started. Since you agree that their definition was correct regarding the terms we were discussing, what was the point of trying to divert the discussion to a point that was not germane to the point? I have to ask, was this trip really necessary? Apparently you seem to think so........ Link to comment Share on other sites More sharing options...
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