What keeps electrons spinning around their nucleus?
in [Relativity]
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From: Gregory L. Hansen on 28 Mar 2005 14:38 In article <StY1e.114735$Ze3.67073(a)attbi_s51>, Sam Wormley <swormley1(a)mchsi.com> wrote: >TomGee wrote: >> Wormy, Bilge, PD, and all you other lemmings, >> >> you cannot understand that it is the _measurement_ of the force which >> is fictional and not the feeling of being pulled out as a carousel >> spins. You cannot make the force disappear just by invalidating your >> own measurements. You should not think that websites are the ultimate >> authority on anything, either, as subjective opinion runs rampart all >> through it. You will learn that, Bilgy, when if ever you get to the >> fifth grade. >> >> TomGee >> > > Poor TomGee--Stuck in the 5th grade--use your playground as a > reference. Your "centrifugal force" disappears. What if he uses himself as the origin? It's only natural, if he's the one making the observation. There's nothing special about the inertial frame and nothing invalid about the accelerated frame. Inertial forces are a common experience and theoretically sound. But the objections that inevitably arise whenever the term "centrifugal" is mentioned seems, to me, tiresome. Who is the person that needs the refresher on physics, the one that doesn't acknowledge that the sensation is really caused by a centripetal acceleration, or the one that thinks mechanics can't be done in an accelerated frame? -- "A nice adaptation of conditions will make almost any hypothesis agree with the phenomena. This will please the imagination but does not advance our knowledge." -- J. Black, 1803.
From: PD on 28 Mar 2005 14:41 Gregory L. Hansen wrote: > In article <1112035436.549412.84900(a)z14g2000cwz.googlegroups.com>, > PD <pdraper(a)yahoo.com> wrote: > > > >TomGee wrote: > >> Wormy, Bilge, PD, and all you other lemmings, > >> > >> you cannot understand that it is the _measurement_ of the force which > >> is fictional and not the feeling of being pulled out as a carousel > >> spins. > > > >Nope. You feel the force pulling you *in*, which is a force you are > ... > >Let me ask you another question. As an elevator suddenly starts to > >descend, you feel lighter. Are you in fact lighter? Why should Earth's > ... > >Let me ask you another question. You are on a road making a circular > >bend left in your car. What force acting on the car enables you to > > Reference frames, Paul. TomGee feels, TomGee is in, TomGee turns... > Who's making the measurement? A hypothetical 2nd observer stationary with > respect to the Earth, or TomGee? > > In those three situations, TomGee is in an accelerated frame. If TomGee > is pushed to the left against a wall, there's an inertial force pushing > him to the left. A 2nd, inertial observer might say no, TomGee is REALLY > being pushed to the right, but so what? He's not in the car. He's just > asserting that there's something special about his reference frame such > that he can make valid observations but TomGee can't, and pretending > there's no valid way to transform between them. > > Centrifugal force is called a force because it acts like a force. It will > cause something to accelerate relative to the stationary observer who's > already pinned against the wall. The stationary observer is, of course, > spinning madly about if viewed by the hypothetical 2nd observer who's > at rest relative to the Earth, but so what? There's nothing special about > the Earth frame, nothing wrong with the accelerated frame. If TomGee is > pinned to the wall of a centrifuge, then TomGee is still at rest with > respect to himself and he can define a reference frame from his > perspective. > -- Yeah, but I'm opposed to this kind of presentation, especially to the uneducated. I really believe that forces should be taught as being characterized by interactions between two objects, and those interactions should be traceable to one of the four (or less) fundamental interactions, and that forces are the cause and accelerations are the effect. Saying that centrifugal force is force because it acts like a force comes at the penalty of losing sight of cause and effect (the acceleration appears to create the force here) and permits the concept of a force without an interaction. Someone who knows to attach the little red flag to this notion while carrying it around can do so with some finesse, but those who are still learning physics should not be encouraged to equivocate. PD
From: PD on 28 Mar 2005 14:44 Sam Wormley wrote: > > > An TomGee thinks this Newtonian perspective has something to do with > the quantum mechanical behavior of electrons... Is he right? No, of course not, but one must correct the simpler and more basic errors first. PD
From: mmeron on 28 Mar 2005 15:42 In article <d29lo4$v6q$1(a)rainier.uits.indiana.edu>, glhansen(a)steel.ucs.indiana.edu (Gregory L. Hansen) writes: >In article <1112035436.549412.84900(a)z14g2000cwz.googlegroups.com>, >PD <pdraper(a)yahoo.com> wrote: >> >>TomGee wrote: >>> Wormy, Bilge, PD, and all you other lemmings, >>> >>> you cannot understand that it is the _measurement_ of the force which >>> is fictional and not the feeling of being pulled out as a carousel >>> spins. >> >>Nope. You feel the force pulling you *in*, which is a force you are >... >>Let me ask you another question. As an elevator suddenly starts to >>descend, you feel lighter. Are you in fact lighter? Why should Earth's >... >>Let me ask you another question. You are on a road making a circular >>bend left in your car. What force acting on the car enables you to > >Reference frames, Paul. TomGee feels, TomGee is in, TomGee turns... >Who's making the measurement? A hypothetical 2nd observer stationary with >respect to the Earth, or TomGee? > >In those three situations, TomGee is in an accelerated frame. If TomGee >is pushed to the left against a wall, there's an inertial force pushing >him to the left. A 2nd, inertial observer might say no, TomGee is REALLY >being pushed to the right, but so what? He's not in the car. He's just >asserting that there's something special about his reference frame such >that he can make valid observations but TomGee can't, and pretending >there's no valid way to transform between them. > >Centrifugal force is called a force because it acts like a force. It will >cause something to accelerate relative to the stationary observer who's >already pinned against the wall. The stationary observer is, of course, >spinning madly about if viewed by the hypothetical 2nd observer who's >at rest relative to the Earth, but so what? There's nothing special about >the Earth frame, nothing wrong with the accelerated frame. If TomGee is >pinned to the wall of a centrifuge, then TomGee is still at rest with >respect to himself and he can define a reference frame from his >perspective. >-- Exactly! Mati Meron | "When you argue with a fool, meron(a)cars.uchicago.edu | chances are he is doing just the same"
From: mmeron on 28 Mar 2005 16:02
In article <1112038415.659261.203550(a)l41g2000cwc.googlegroups.com>, "PD" <pdraper(a)yahoo.com> writes: > >TomGee wrote: >> Wormy, Bilge, PD, and all you other lemmings, >> >> you cannot understand that it is the _measurement_ of the force which >> is fictional and not the feeling of being pulled out as a carousel >> spins. You cannot make the force disappear just by invalidating your >> own measurements. You should not think that websites are the >ultimate >> authority on anything, either, as subjective opinion runs rampart all >> through it. You will learn that, Bilgy, when if ever you get to the >> fifth grade. >> >> TomGee > >One more little experiment, Tom, on your carousel. Take your >pocketwatch on the carousel with you and hang it by its chain between >your thumb and forefinger. If you don't have a pocketwatch, take your >wristwatch and hang it by a string in the same way. Now have someone >spin you up on the carousel. > >You see the watch swings outward on the chain. Why, you ask? Is it >centrifugal force? No, your fourth grade teacher says, look again. Yes, that's probably what the teacher will say. physics teachers know little physics. There is ***nothing*** wrong with centrifugal force. The term "fictitious" is misleading. True, it doesn't stem from interaction, just from chice of reference frame. So? It is quite often convenient to deal with a problem in an accelerated frame, rather than transform to an inertial frame and back. And when you want to deal with a problem in the accelerated frame and still use Newton's laws, you include inertial forces (i much prefer the term "inertial" than the misleading "fictitious"). Try the following problem. Assume that you've, say, the space shuttle in a circular orbit around Earth, with a small mass placed in the middle of the cargo hold, motionless relative to the shuttle. Now give it a slight nudge. Write the Lagrangian for the system, in the shuttle coordinates and observe the equations of motion. You'll find a centrifugal term (and a Coriolis term, as well). Of course, if you'll use an inertial frame, insted, these terms will disappear. But you'll find the inertial frame far less convenient. It is a matter of pragmatism, not ideological soap boxes. Consider the equation ax^2 + bx + c = 0 I'm sure that you're aware that one can always eliminate the middl (linear) term by a proper shift of the origin of x. So? Do we call this middle term "fictitious" and warn students never to use it? That would be nonsense. Mind you, this has nothing to do with the value of TomGee's gibberish. But then, since you chose to waste your time by responding to him ... Mati Meron | "When you argue with a fool, meron(a)cars.uchicago.edu | chances are he is doing just the same" |