What keeps electrons spinning around their nucleus?
in [Relativity]
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From: Creighton Hogg on 30 Mar 2005 20:41 On Wed, 30 Mar 2005 mmeron(a)cars3.uchicago.edu wrote: > In article <g3G2e.18186$C7.13173(a)news-server.bigpond.net.au>, "Bill Hobba" <bhobba(a)rubbish.net.au> writes: > > > ><mmeron(a)cars3.uchicago.edu> wrote in message > >news:j7E2e.47$45.6426(a)news.uchicago.edu... > >> In article <e9adncBCPNmLCdffRVn-uw(a)rcn.net>, jmfbahciv(a)aol.com writes: > >> >In article <f1l2e.34$45.5068(a)news.uchicago.edu>, > >> > mmeron(a)cars3.uchicago.edu wrote: > >> >>In article <pPmdnT872IUW8tTfRVn-rw(a)rcn.net>, jmfbahciv(a)aol.com writes: > >> >>>In article <7K52e.21$45.3808(a)news.uchicago.edu>, > >> >>> mmeron(a)cars3.uchicago.edu wrote: > >> >>>>In article <Xns9627C5AEB62D6WQAHBGMXSZHVspammote(a)130.39.198.139>, bz > >> >>><bz+sp(a)ch100-5.chem.lsu.edu> writes: > >> >>>>>mmeron(a)cars3.uchicago.edu wrote in > >> >>>>>news:8B12e.18$45.3391(a)news.uchicago.edu: > >> >>>>> > >> >>>>>> In article <Mo12e.16031$C7.902(a)news-server.bigpond.net.au>, "Bill > >> >>>Hobba" > >> >>>>>> <bhobba(a)rubbish.net.au> writes: > >> >>>>>>> > >> >>>>>>><mmeron(a)cars3.uchicago.edu> wrote in message > >> >>>>>>>news:XQ02e.15$45.3352(a)news.uchicago.edu... > >> >>>>>>>> >coordinates, but I think what is misleading is to call the > >> >>>correction > >> >>>>>>>> >terms "forces". > >> >>>>>>>> > >> >>>>>>>> Only if you attach more meaning to the term "force" than it > >> >deserves. > >> >>>>>>> > >> >>>>>>>Ahhhhhh. Yes. As Feynman says it is half a law. It gains its > >full > >> >>>>>>>meaning when combined with other laws and/or concepts such as > >> >Coulombs > >> >>>>>>>law or the introduction of non inertial reference frames. > >> >>>>>>> > >> >>>>>> Yes, it is a rather complex issue. I wrote some stuff about it in > >> >the > >> >>>>>> past, here, but I never kept a copy. But it certtainly needs some > >> >>>>>> sort of broad framework, to make sense. > >> >>>>> > >> >>>>>Especially when someone keeps insisting that force is always the > >result > >> >>>of > >> >>>>>acceleration > >> >>>> > >> >>>>Cause, not result. > >> >>>> > >> >>>>> and that without acceleration (as for example when a gyro > >> >>>>>precesses at a constant rate, or when a mass moves at a constant > >> >velocity > >> >>>>>because it is overcoming drag or friction) there is no force and no > >> >work. > >> >>>>> > >> >>>>Where there is net force, there is acceleration. The F in Newton's > >> >>>>law is the total (i.e.) net force acting. Since forces are vectors, > >> >>>>it is perfectly possible to have different non-zero forces to sum up > >> >>>>to a zero net force. > >> >>> > >> >>>This is why using algebra in first physics courses hurts learning > >> >>>more than it helps. > >> >>> > >> >>I don't see why it should hurt. Of course, it is better if you can > >> >>use calculus, not just algebra. > >> > > >> >Oh, it hurts because the concept of changes doesn't show up > >> >when doing the math. > >> > >> Well, that's true. Newton had good reasons to create calculus, > >> without it you're mostly limited to static situations. Unfortunately, > >> though, high schools teach calculus late (if at all). > > > >Is that true Mati? Here in Australia it is taught in grade 11 and 12 (which > >would make the students 16 and 17) And last I heard it was being taught in > >some private schools in grade 9 and 10 which I thought was a positive move. > >I wonder why? I learnt about it when I was 14 and had no trouble. > > > Well, you have to realize that in the US there is no such thing as > nationwide (or even state wide) public school curriculum. Policies > are set on the school district level and the population a given > school district serves may range in size from 10-20 thousand to few > millions. So, it is quite possible to have high schools in > neighboring towns at widely different levels (yes, I'm aware that even > where the schools are nominally all the same, they're not really so, > but the differences here are larger). > > This said and done, in any US public school I know, calculus is taught > (not to all, only the students who opt to take it) in grade 12 (with a > possibility of a bright 11 grader taking it as en elective). Indeed this is the case as I've seen it as well. I learned it on my own in 10th grade because I was bored and frustrated. There's no reason why kids that age can't handle it.
From: TomGee on 30 Mar 2005 23:41 Tom Capizzi wrote: > "TomGee" <lvlus(a)hotmail.com> wrote in message > news:1112061355.884198.62110(a)g14g2000cwa.googlegroups.com... > > > > PD wrote: > SNIP > > > Centrifugal forces don't exist. They are mistakes of perception and no force > actually pushes out. > > Not so. The inertial force of a mass wants it to go straight but the gravitational force wants it to turn and if an orbit results the net force is on the side of gravity but just enough to pull it into orbit. > >> > >> > >> If this comes as a shock to you, perhaps it's because > >> you're relying on the physics you learned in the 3rd grade. > >> 3. In circular motion, you'll note that the velocity is tangent to > > the > >> circular trajectory, perpendicular to the radius of the circle. Both > >> the true, centripetal force and the false, centrifugal "force" are > >> along the radius of the circle, perpendicular to the velocity. > >> > >> > > Velocity is a vector but you are using it to mean "direction". Speed > > cannot be tangent nor perpendicular to anything, so you're babbling > > now. > > Talking about yourself again? Vector: > 2. (Math.) A directed quantity, as a straight line, a force, or a velocity. > Vectors are said to be equal when their directions are the same their > magnitudes equal. Cf. Scalar. [1913 Webster] > > That's what I said, velocity is a vector. It is also "speed", but that is not what he means. If he is saying that the forces are imposed perpendicular to the speed, if he means to use velocity for speed, that would be nonsense, as I noted above. If he means to say that the direction of the mass quantity is tangent to the path of the object (trajectory), that too makes no sense. > > > >> There is > >> no way that a force that is perpendicular to the velocity can change > >> the magnitude of the velocity, nor does it help in any way to > > maintain > >> the velocity. > >> > >> > > Mygawd Im talking to a child! There is no magnitude in velocity! It > > is a measure of the rate of change of position of something wrt time, > > speed, and direction. > > See above definition of vector. Clearly it has magnitude. You don't know > what you are talking about again. > > If magnitude and quantity had the same meaning, we would have use for only one and not both. > > > > >> 4. Newton's 1st law should also have been taught to you in 3rd grade > >> physics, and you should be reminded that, even in the absence of > >> forces, objects in motion tend to stay in motion. > >> > >> > > I can't believe you are so ignorant as to claim that the 2nd law allows > > objects to remain in orbit if all forces are removed. I let that > > foolishness go by the first time you said it, to keep from making you > > look sillier, but it is you who brings that onto yourself, not me, with > > your absurdities. > > Look again. It says 1st law. If you actually read the 1st law you would know > that it says motion "in the same direction", that is to say a straight line, > unless acted on by unbalanced forces. > > If you actually understood what is being said you would know circular motion is not a straight line. Or do you agree with Silly there that objects in circular motion, orbits or orbitals, will continue in such motion even when the forces maintaining them in such motion are removed? > >> > >> > >> Now, if you find any of this to be intuitively wrong, then your > > problem > >> is not with special relativity, it's with 3rd grade physics. If you > >> would like corroboration that any of the above is true or false, then > >> simply itemize the thing you think is wrong and ask the newsgroup. > >> > >> > > All but a few have dared to agree with me or disagree with you, but, as > > I said in my first post in this thread, I find it incredible that the > > first 8 posters could not answer a simple question properly. Either > > they all think you're the greatest thing since Einstein or they will > > agree to anything so long as they don't have to agree with me. > > > > The question was what keeps the electron spinning around the nucleus, not > what keeps it attracted. Maybe they are the same thing to you, but they are > actually perpendicular directions. In physics, perpendicular components, > even of the same vector, are independent. If you wanted to know what > attracts the electron, you should have asked a better question. Of course, > it seems you already had the answer you wanted, but were trying to bait a > troll's trap. > > Hey, I did not ask the questions. You seem to think that the question was what keeps it moving? It was not. He asked what keeps it moving _around the nucleus_, as you correctly state above. You don't seem to see the distinction between those two questions, but that is not my fault. Something keeps free electrons moving, and as free electrons, they are not then moving around any nucleus. Since the question was that specific, so was my answer. TomGee
From: mmeron on 31 Mar 2005 01:44 In article <Pine.LNX.4.44.0503301941040.20954-100000(a)dill.hep.wisc.edu>, Creighton Hogg <wchogg(a)hep.wisc.edu> writes: > > >On Wed, 30 Mar 2005 mmeron(a)cars3.uchicago.edu wrote: > >> In article <g3G2e.18186$C7.13173(a)news-server.bigpond.net.au>, "Bill Hobba" <bhobba(a)rubbish.net.au> writes: >> > >> ><mmeron(a)cars3.uchicago.edu> wrote in message >> >news:j7E2e.47$45.6426(a)news.uchicago.edu... >> >> In article <e9adncBCPNmLCdffRVn-uw(a)rcn.net>, jmfbahciv(a)aol.com writes: >> >> >In article <f1l2e.34$45.5068(a)news.uchicago.edu>, >> >> > mmeron(a)cars3.uchicago.edu wrote: >> >> >>In article <pPmdnT872IUW8tTfRVn-rw(a)rcn.net>, jmfbahciv(a)aol.com writes: >> >> >>>In article <7K52e.21$45.3808(a)news.uchicago.edu>, >> >> >>> mmeron(a)cars3.uchicago.edu wrote: >> >> >>>>In article <Xns9627C5AEB62D6WQAHBGMXSZHVspammote(a)130.39.198.139>, bz >> >> >>><bz+sp(a)ch100-5.chem.lsu.edu> writes: >> >> >>>>>mmeron(a)cars3.uchicago.edu wrote in >> >> >>>>>news:8B12e.18$45.3391(a)news.uchicago.edu: >> >> >>>>> >> >> >>>>>> In article <Mo12e.16031$C7.902(a)news-server.bigpond.net.au>, "Bill >> >> >>>Hobba" >> >> >>>>>> <bhobba(a)rubbish.net.au> writes: >> >> >>>>>>> >> >> >>>>>>><mmeron(a)cars3.uchicago.edu> wrote in message >> >> >>>>>>>news:XQ02e.15$45.3352(a)news.uchicago.edu... >> >> >>>>>>>> >coordinates, but I think what is misleading is to call the >> >> >>>correction >> >> >>>>>>>> >terms "forces". >> >> >>>>>>>> >> >> >>>>>>>> Only if you attach more meaning to the term "force" than it >> >> >deserves. >> >> >>>>>>> >> >> >>>>>>>Ahhhhhh. Yes. As Feynman says it is half a law. It gains its >> >full >> >> >>>>>>>meaning when combined with other laws and/or concepts such as >> >> >Coulombs >> >> >>>>>>>law or the introduction of non inertial reference frames. >> >> >>>>>>> >> >> >>>>>> Yes, it is a rather complex issue. I wrote some stuff about it in >> >> >the >> >> >>>>>> past, here, but I never kept a copy. But it certtainly needs some >> >> >>>>>> sort of broad framework, to make sense. >> >> >>>>> >> >> >>>>>Especially when someone keeps insisting that force is always the >> >result >> >> >>>of >> >> >>>>>acceleration >> >> >>>> >> >> >>>>Cause, not result. >> >> >>>> >> >> >>>>> and that without acceleration (as for example when a gyro >> >> >>>>>precesses at a constant rate, or when a mass moves at a constant >> >> >velocity >> >> >>>>>because it is overcoming drag or friction) there is no force and no >> >> >work. >> >> >>>>> >> >> >>>>Where there is net force, there is acceleration. The F in Newton's >> >> >>>>law is the total (i.e.) net force acting. Since forces are vectors, >> >> >>>>it is perfectly possible to have different non-zero forces to sum up >> >> >>>>to a zero net force. >> >> >>> >> >> >>>This is why using algebra in first physics courses hurts learning >> >> >>>more than it helps. >> >> >>> >> >> >>I don't see why it should hurt. Of course, it is better if you can >> >> >>use calculus, not just algebra. >> >> > >> >> >Oh, it hurts because the concept of changes doesn't show up >> >> >when doing the math. >> >> >> >> Well, that's true. Newton had good reasons to create calculus, >> >> without it you're mostly limited to static situations. Unfortunately, >> >> though, high schools teach calculus late (if at all). >> > >> >Is that true Mati? Here in Australia it is taught in grade 11 and 12 (which >> >would make the students 16 and 17) And last I heard it was being taught in >> >some private schools in grade 9 and 10 which I thought was a positive move. >> >I wonder why? I learnt about it when I was 14 and had no trouble. >> > >> Well, you have to realize that in the US there is no such thing as >> nationwide (or even state wide) public school curriculum. Policies >> are set on the school district level and the population a given >> school district serves may range in size from 10-20 thousand to few >> millions. So, it is quite possible to have high schools in >> neighboring towns at widely different levels (yes, I'm aware that even >> where the schools are nominally all the same, they're not really so, >> but the differences here are larger). >> >> This said and done, in any US public school I know, calculus is taught >> (not to all, only the students who opt to take it) in grade 12 (with a >> possibility of a bright 11 grader taking it as en elective). > >Indeed this is the case as I've seen it as well. I learned >it on my own in 10th grade because I was bored and >frustrated. There's no reason why kids that age can't >handle it. > Try to explain this to the school boards (and be prepared to face charges of elitism). Mati Meron | "When you argue with a fool, meron(a)cars.uchicago.edu | chances are he is doing just the same"
From: Harry on 31 Mar 2005 03:00 "TomGee" <lvlus(a)hotmail.com> wrote in message news:1112169255.641966.61840(a)f14g2000cwb.googlegroups.com... > > PD wrote: > > Harry wrote: > > > <mmeron(a)cars3.uchicago.edu> wrote in message > > > news:7K52e.21$45.3808(a)news.uchicago.edu... > > > > SNIP > > > > > > Right. Active forces (or how to call them, I think Newton called > them > > > impressed forces) cause acceleration. But a centrifugal force is a > > > reaction force > > > > Ack! Not in Newton's sense of action and reaction. > > > Sure it is. It is the inertial force's reaction to the centripetal > force of gravitation which can balance out to keep objects in orbit. > > > > > > > to a centripetal force, which is caused by a change in direction. > > > > Ack! Confusing cause and effect. The force causes the change in > > direction, not the other way around. > > > Yes, it causes the object to orbit instead of fleeing out and away. I see, I forgot to mention that I discussed the case of an object on a rope, like Newton did. In this case it's the change of direction that causes the force. > > > I > > > wouldn't describe such as "pseudo force" or "fictional" force, as > > that gives > > > the wrong impression that no real force is exerted. > > > > Again, if you consider it carefully, it's not that complicated. If > you > > are rear-ended in your car, the reason your neck gets hurt is because > > your body accelerates forward and your head does not. There is no > need > > to assert a force exerting backwards on your head to account for this > > (although it would appear that there was one in a frame that > > accelerates forward in impact). > > > > PD > > > > > Wrong, PD. The inertial force of your head works against the > acceleration caused by the crash since it is loosely connected to your > body. If it did not - i.e., if it was frozen to your body - your neck > would not get hurt, barring any other harm-causing events. Correct. It's a reaction force to acceleration. PD is right that it isn't a force that exerts backwards on the head. As long as the head is not stopped, there is no force. What can do harm is the force of the head acting on the neck and it's as real as the force of the neck acting on the head. > > > In reality such forces > > > are real enough to break your neck! Newton also didn't call them > > "pseudo" or > > > "fictional", AFAIK; he just called them innate/inertial forces. > > > > > > Harald > > > > > Yes, Harald, that is exactly what he called them. Harald
From: Y.Porat on 31 Mar 2005 05:27
you are mingling a case of a force that acts on a *conglomeration of particles* with a case of a force acting on a *single* particles in a similar way thee is a difference between daling with a conglomeration body *as one unit* without entering into the intrinsic actione in it and another case of examining a conglomeration body in analysing the intrinsic forces between the conglomeration partners. and just another general remark to your discussion it is a vaine discusion once you look at the title of this thread because : the electron *does not orbit at all around the nuc there i s no relative translation between electron and nuc and no angular relative translation between the electron and the nuc. just vibration of the electron that is connected on one of its edges to the nuc . so you are grinding straw - enthousiastically.(and wasting your unpreciouis time ) ----------------------- all the best Y.Porat -----------------------------. |