Talk:Centrifugal force

Archives

April 2004 June 2004 – January 2006 January 2005 – November 2006 February 2007 – April 2007 January 2007 – March 2008 April 2008 May 2008 June 2008 July 2008 – August 2008 September 2008 October 2008 August 2008 – May 2009 May 2009 – June 2009 June 2009 – ???

Layman's terms

Can someone add an English version? Seriously, way too technical for a Wikipedia entry from paragraph one. --66.119.170.242 (talk) 00:53, 29 January 2011 (UTC)

Bloat

This article was intended to be summary style, but it keeps accumulating bloat. Brews ohare reverted my latest attempt to remove unnecessary junk that was recently added to a section (I was responding to someone's suggestion that a cleanup was needed). Can anyone comment on whether it's helpful to have that level of detail in a summary of another article? Dicklyon (talk) 02:49, 19 August 2010 (UTC)

I removed the detailed material that you removed, but with an explanation (immediately above). I left the "Common experiences" portion, which seems to me appropriate for such a preliminary article. Brews ohare (talk) 05:41, 19 August 2010 (UTC)

And now you've got that as part of "Context and Usages", which says its main article is "Centrifugal force (rotating reference frame)". Can you repair that at least? Dicklyon (talk) 05:59, 19 August 2010 (UTC)

Now that the latest ado has reached some kind of definitive consequences, I'm in agreement with you, Dicklyon. I think your removal of bloat was warranted and an improvement, and I'd support redoing it (in fact I think I'll go do that right now). There might have been a few references for the Lagrangian formulation that brews added in that it might be worth salvaging, but overemphasis on the lagrangian usage by be a bit undue weight.

In line with this, I think there are a few other concerns that I have.

• The "See also" section needs trimming so it matches the manual of style.
• The section headings could use tweaking - mainly I'm looking at the 4th item in WP:MOSHEAD and some of the guidelines on article titles.
• Finally, I still don't understand why we have both this article and Centrifugal force (disambiguation). It seems like both pages are trying to do the same thing. Perhaps I'll make a subsection just for this item since I could see discussion on this getting pretty lengthy.

--FyzixFighter (talk) 21:09, 22 August 2010 (UTC)

Re-merging

Right now we have at least three separate pages (this page, a disambiguation page, and one specific to rotating reference frames) and a lot of overlap in material and in function. For example, this page and Centrifugal force (disambiguation) are performing nearly the same function. Perhaps someone knows the rational for why we have both of them? I'm wondering if we can't re-merge this page and Centrifugal force (rotating reference frame), since a good argument could be made (imo) that the rotating reference topic is the primary topic. That way the disambiguation page can still exist (to help distinguish between this and the Reactive centrifugal force). The only aspect that might not nicely fit is the Lagrangian formulation but which is (afaik) a very limited and slightly esoteric usage. I could very easily see that as a subsection. I could be wrong on this point, in which case it could be spun off into a separate article (Centrifugal force (Lagrangian mechanics) perhaps), but I still think the rotating reference frame should be the primary topic rather than the expanded faux disambiguation page we have now. Thoughts? --FyzixFighter (talk) 19:53, 13 September 2010 (UTC)

I would agree with a three way merge, between Centrifugal force, Reactive centrifugal force and Centrifugal force (rotating reference frame). The latter two seem far less encyclopaedic than they should be, with a surplus of examples and large, confusing diagrams needing overlong captions to explain them (and even then they are unclear). If the unencyclopaedic content were pared back it could be merged into the sections in Centrifugal force and I don't think the resulting article would be too large.

The DAB page I think should stay for now, though once the articles are merged this could be reassessed, as what would be left might be too trivial - there would only be one page on centrifugal force. But the page at Centrifugal force (disambiguation) has no content and would not get in the way of the merge, so need not be considered.--JohnBlackburne^words_deeds 20:23, 13 September 2010 (UTC)

For the most part I agree with you John, especially on the paring of surplus (imo, textbook-y) examples. The only difference in opinion I have is I would not advocate merging Reactive centrifugal force back in. The two are sufficiently distinct physical concepts (one's a fictitious force and frame dependent, the other a very real force that exists independent of frame; they will only equal in magnitude in a co-rotating frame) that I think separate articles are warranted. The concept of reactive centrifugal force is also a very common in engineering and one doesn't have to go searching for esoteric sources to find some that clearly make the distinction between the two. IIRC, one of the reasons for spinning it off was that one or two editors were constantly confusing the two and making the claim that they were the same thing. That isn't to say that Reactive centrifugal force couldn't use some paring and de-bloating, but I believe that there could still be enough information there to warrant its own article.

I should probably add some merger tags as a courtesy and to encourage others to chime in. --FyzixFighter (talk) 16:30, 14 September 2010 (UTC)

I think you should do away with the disambiguation page, since I can't see what it's for, but leave the summary-style centrifugal force article, and keep the other bloated articles separate (and separately work on de-bloating them). Dicklyon (talk) 04:18, 15 September 2010 (UTC)

I would support this merger idea. One single article is all that is required for the topic 'centrifugal force'. David Tombe (talk) 11:42, 21 October 2010 (UTC)

It wasn't a merger idea, so it's not clear what you're supporting. Dicklyon (talk) 20:51, 21 October 2010 (UTC)

Dick, the title of this section says re-merging, and from reading the lead that is what the author seems to be advocating, and I am supporting the re-merger. We only need one 'centrifugal force' article. The Germans don't have a multitude of articles on 'centrifugal force'. David Tombe (talk) 00:17, 22 October 2010 (UTC)

But your reply to me above seemed to say you were supporting me; sorry I misunderstood. Dicklyon (talk) 05:42, 22 December 2010 (UTC)

So everybody involved in this discussion supports the re-merge, but two months later it hasn't happened yet. Why not? (I support it too FWIW.) Alzarian16 (talk) 20:48, 21 December 2010 (UTC)

Well, not quite. I agreed with getting rid of the new disambiguation article, but keeping the summary-style article (this one) and keeping the bigger and more specific articles (the ones I called "bloated") separate. I went ahead and merged the disambig (by redirecting it here, since there was nothing else to do). Dicklyon (talk) 05:40, 22 December 2010 (UTC)

JohnBlackburne and FyzixFighter, do you have a merge plan that would get rid of some of the 48 KB of Brews ohare's bloat from Centrifugal force (rotating reference frame) as you merge? I might consider agreeing to a merge if I didn't think it would just add a lot of junk to what's currently not such a bad article. Dicklyon (talk) 05:46, 22 December 2010 (UTC)

My suggestion would be to merge only the first three sections of Centrifugal force (rotating reference frame) and drop the rest entirely, but I'd guess that others would probably disagree. Alzarian16 (talk) 18:26, 22 December 2010 (UTC)

I would just trim the article as it is now: it's something that I've thought of before but never got around too, but even as a standalone article there's too much bloat from Advantages of rotating frames onwards, and too many references for them to be useful. It should be easy to do now without Brews's disruptive objections.--JohnBlackburne^words_deeds 19:12, 22 December 2010 (UTC)

The Lagrangian section could do with considerable trimming also. I think this is a specialist and somewhat informal use of the term. Martin Hogbin (talk) 18:14, 22 December

I'm opposed to the merge. This article is the sister article of coriolis effect and shouldn't be merged with others. It's a completely different topic; the maths is different, and the equation that it comes out of is different one.Planetscared (talk) 17:00, 13 January 2011 (UTC)

I get the feeling that you have confused the merge here. The proposal entails a merge of Centrifugal force (rotating reference frame) into Centrifugal force. How are those a completely different topic? Yoenit (talk) 17:39, 13 January 2011 (UTC)

I'm opposed, too. I think this is a stale proposal, that we partially fulfilled by phasing out the disambig page. If someone still thinks that it's important to do more merging, they should speak up right away, or start a new proposal explaining why. Dicklyon (talk) 19:18, 13 January 2011 (UTC)

Dick, are you against merging Centrifugal force (rotating reference frame) into Centrifugal force? It seems like a good idea to me. ~~

Yes, I Oppose the merge, because, as I've explained before, Centrifugal force is a summary-style article that introduces the deeper treatments in Centrifugal force (rotating reference frame), Reactive centrifugal force, Absolute rotation, History of centrifugal and centripetal forces, and other articles. This seems like exactly the right place to have a summary-style article. Dicklyon (talk) 23:07, 13 January 2011 (UTC)

I do not believe that a disambiguation page is desirable. There is only one definition of centrifugal force in widespread modern use and that is Centrifugal force (rotating reference frame). A disambiguation page is in my opinion confusing to the general reader and gives undue weight to specialist, historical, or fringe meanings of the term. Martin Hogbin (talk) 12:45, 14 January 2011 (UTC)

I agree with you that a disambiguation page is not desirable here; that's why I eliminated it. I'm not sure why Wolfkeeper created it in the first place, or why Brews felt a need to bloat it to over 1600 bytes, but now it's gone. As for your assertion that "There is only one definition of centrifugal force in widespread modern use," that's sort of true, but a lot of disclaimers. Some dispatch to the other less modern, less widespread, and related points of view is still important, I think. A summary article is a good way to let the reader know what the different aspects are; for most, it's all they'll need. Or are you saying that some of the other articles are just junk that should be eliminated? Dicklyon (talk) 16:17, 14 January 2011 (UTC)

I am thinking of how this looks to an average reader who wants to know what centrifugal force is, or maybe a student needing some help on the subject. At the moment they see two articles, suggesting that the term has two, or more meanings. Personally, I would like to see one article on the standard modern meaning of the with short sections on historical or other meanings. Martin Hogbin (talk) 22:43, 14 January 2011 (UTC)

Dicklyon, anybody with a reasonable comprehension of the subject would know that there is only one 'centrifugal force', and that a single article could very easily accomodate all of the various perspectives on the matter. What you seem to have failed to grasp is that there is a big difference between,

(1) considering centrifugal force to be a fictitious force as viewed from a rotating frame of reference, and (2) considering centrifugal force to be a radially outward inertial force that arises in conjunction with absolute rotation, and which is revealed when Newton's laws are expressed in a rotating coordinate system such as polar coordinates.

The former involves the idea that centrifugal force even exists when an object is not co-rotating with the rotating frame, while the latter attributes centrifugal force specifically to absolute angular momentum. The two perspectives overlap in the co-rotating scenario, but it is unnecessary to involve a rotating frame of reference when doing planetary orbital analyis. David Tombe (talk) 11:44, 14 January 2011 (UTC)

David, a rotating coordinate system is the same as a rotating frame of reference. Fictitious forces and inertial forces are two terms for the same thing. In the context of a rotating frame of reference (or coordinate system) rotating refers to absolute rotation. The distinction you make simply does not exist. Martin Hogbin (talk) 22:43, 14 January 2011 (UTC)

Martin, Part of what you are saying is right. I agree with you that centrifugal force is a single topic. I also agree that most modern textbooks introduce it as a fictitious force that is observed in a rotating frame of reference. I also agree with you that that the words 'fictitious' and 'inertial' are used inter-changeably in the modern literature. But you are also overlooking some important factors. When an object is co-rotating with a rotating frame of reference, the centrifugal force will be an inertial effect which can actually be felt pushing outwards. However, within the context of the 'rotating frame of reference' perspective, if an object is stationary and not co-rotating with the rotating frame of reference, it is still deemed to be subjected to a centrifugal force based on the angular speed of the frame of reference. That is where this approach differs from the polar coordinates approach.

When we deal in polar coordinates, we are only concerned with the centrifugal force that arises in connection with absolute rotation, and which can be felt physically pushing outwards. And it is this perspective which is used in planetary orbital analysis where the rotation doesn't in general have a uniform angular speed. In other words, there is a branch of physics in which we consider centrifugal force as an outward radial force, and in which we don't normally invoke the concept of a rotating frame of reference, and in which the centrifugal force is induced by absolute rotation. This perspective needs to have a section of its own in the article.

What I would like to ask you is 'what category do you place this latter perspective in? Is it specialist? Or is it fringe? Or is it historical?' I would say that it is general and historical. It was originally devised by Leibniz, and it is used today in planetary orbital analysis. At any rate, we have identified two different perspectives on centrifugal force. We have one in which it is a fictitious force which is a function of the rotating frame of reference, whether the object is co-rotating or not. And we have another in which the centrifugal force is an inertial force which can be physically felt and which is a product of absolute rotation, and which doesn't require the concept of a rotating frame of reference. Both of these perspectives are sourced, although I admit that the former is currently much more widely sourced. David Tombe (talk) 23:17, 14 January 2011 (UTC)

It's essentially unsourced, idiosyncratic, and fringe. Goldstein made it clear enough that radial distance is a coordinate in a rotating coordinate system, not a concept different from the usual. Dicklyon (talk) 00:06, 15 January 2011 (UTC)

David, you seem completely confused, I suggest that we continue this discussion on your talk page. Martin Hogbin (talk) 02:19, 15 January 2011 (UTC)

OK. We'll go there. But based on what you have written above, I am guessing that you have done one of those university courses in applied maths entitled 'rotating frames of reference' in which the coordinate transformations are done, and where centrifugal force and Coriolis force emerge and are introduced as fictitious effects which are a product of observation from the rotating frame. That of course, despite being prolific in modern textbooks, is a specialist approach for advanced mathematicians and it is not the common understanding of centrifugal force amongst the public at large. The public at large think of centrifugal force as being the outward radial pressure which arises when something is spun. And the common understanding is the one that is used in planetary orbital analysis. Anyway, by all means carry on on my talk page. David Tombe (talk) 11:44, 15 January 2011 (UTC)

The James Bond Cartoon

There was alot of fuss about a James Bond cartoon while I was away and I didn't get the chance to state my 2 cents. The cartoon should not be in the main article, but it makes an excellent basis for a talk page discussion for the purpose of improving the article. The cartoon highlights the controversy very clearly. And here is an even better cartoon. Check out card number 12 at this weblink [1]. David Tombe (talk) 19:49, 21 October 2010 (UTC)

five different contexts?

I just reverted this edit which changed the description of the two types of centrifugal force, fictitious and reactive, into I'm not sure what. I had a look at the source for the 'five different contexts' but could not find it, and frankly the source is very poor one, a long and poorly written essay which is no substitute for the reliable academic sources already in the article. More generally if there is some source which introduces new material it should be worked into the article alongside existing material, not added to the lede in a way which disagrees with the rest of the article.--JohnBlackburne^words_deeds 17:31, 6 November 2010 (UTC)

John, it was in the paragraph third from the bottom. It read,

Thus Newton uses the term “centrifugal force” in the Principia to describe three very distinct concepts. First, he uses it to refer to a hypothetical repulsive force (such as the force between two electrons), which would result in a hyperbolic path, accelerating away from the source of the “central” repulsive force. Second, he uses the term to refer to the outward force exerted by a revolving object on some framework (such as the force exerted by a roulette marble on the housing). Third, he uses the term to refer to the “fictitious” outward force on a revolving object when viewed from a revolving frame of reference. A fourth context in which the concept of “centrifugal force” may arise is when phenomena are described in terms of curved coordinate systems, such as polar coordinates. Such non-linear coordinate systems are not inertial in the spatial sense, even though they may be static (i.e., not accelerating), as discussed in the note on Curved Coordinate Systems and Fictitious Forces. A fifth usage of the term “centrifugal force” occurs when the inertial forces on an object, relative to a momentarily co-moving inertial frame, are de-composed into tangent and normal components (in the osculating plane). The normal component is called centrifugal force. There is no Coriolis force with this convention, because the particle is always at rest with respect to the co-moving inertial coordinates. Needless to say, all these usages are very closely related, and differ only by context and convention.

You cannot leave the article lead stating that there are only two concepts of centrifugal force when there are clearly more. Polar coordinates is one such context. That is the context which is used in planetary orbital analysis. It is not something which is in any doubt. David Tombe (talk) 17:44, 6 November 2010 (UTC)

What Newton thought might be of interest historically but physics has moved on a long way since his time, in both what we know and how we describe it. From my reading of that he used it for more than we would today: e.g. the first example of repulsing electrons. But no, there are two concepts as expressed in the article and it summarises in the lede. And that essay hardly seems a reliable source: more a personal essay by someone with some odd views, on a web site created to push his self-published book.--JohnBlackburne^words_deeds 17:57, 6 November 2010 (UTC)

John, The article mentioned three concepts in connection with Newton. I had discounted the first concept in my count of five. Newton's other two concepts are exactly the same two concepts that you have already accepted. Ie. the reactive force and the inertial force in a rotating frame of reference. So you should have no problem with the bit about what Newton said. The article then went on to talk about polar coordinates. That is not in any doubt. We formulate the planetary orbital equation in polar coordinates and the radial equation has an outward centrifugal force term. Then he mentioned about normal and tangential resolutions of velocity. I found his remarks about 'no Coriolis force' in this system to be very interesting. I see no grounds for you to either doubt what the author has said, or to deem the source to be unreliable.

And for your information, in my own personal opinion, there is only one single concept of centrifugal force. In my view, four of the five mentioned in the source are one and the same thing. The so-called reactive force is merely a knock-on effect of the inertial force, just as a brick falling on somebody's head is a knock-on effect of gravity. David Tombe (talk) 18:12, 6 November 2010 (UTC)

None of this really matters. The Mathpages is a very intereresting work (- i.m.o. it is piece of art -) but it can never serve as an authoritative source as a basis for Wikipedia content. It is someone's personal (and, apart from one chapter, book-unpublished) view. It clearly is an ideal entry for the External links section, and perhaps even for the Further reading list, but the unpublished parts can never be used as a wp:RS, and can certainly never replace a solid textbook source. DVdm (talk) 18:37, 6 November 2010 (UTC)

Dvdm, Is your only concern about a solid textbook source which uses polar coordinates as an illustration of centrifugal force? Are you seriously doubting that centrifugal force is a polar coordinate term in the radial planetary orbital equation? David Tombe (talk) 19:07, 6 November 2010 (UTC)

Even if it were properly sourced the introduction is not the place to introduce sourced material. It should be introduced into the body of the article, properly integrated in what is a well established article. As for the content I still find what you added confusing and unclear, in particular what you mean by context. Polar coordinates are just another coordinate system, but there are an infinite number of them, any of which could be used to calculate the force, as they are largely interchangeable – Lagrangian mechanics is one way of approaching this. It's not clear what "normal and tangential resolutions of velocity" have to do with centrifugal force. And the others are what is there already, and in the article.--JohnBlackburne^words_deeds 19:45, 6 November 2010 (UTC)

John, It's a simple yes or no question. Do you accept the fact that centrifugal force is a term in polar coordinates which is used in the radial planetary orbital equation without involving rotating frames of reference? David Tombe (talk) 19:53, 6 November 2010 (UTC)

Take your questions to the ref desk if you don't understand the topic. If this is about the article I don't see how your question relates to it. Perhaps you could point to the section of the article you think is wrong and suggest a, reliably sourced, way to improve it.--JohnBlackburne^words_deeds 19:57, 6 November 2010 (UTC)

John, You didn't answer the question. The section in the article which you are asking about doesn't exist for the reason that some editors in the past have rejected the idea that centrifugal force is a term in the radial planetary orbital equation. I have supplied a source which states that centrifugal force is a term in polar coordinates outside of the context of rotating frames of reference. Do you have any objections to that material being put into the article on the basis of your own beliefs, or is it purely a matter of whether or not the source is reliable? David Tombe (talk) 20:08, 6 November 2010 (UTC)

Everything here needs a reliable source, and you have yet to supply one; it has nothing to do with "my beliefs".--JohnBlackburne^words_deeds 20:23, 6 November 2010 (UTC)

See also this new entry at the Wikipedia:Reliable sources/Noticeboard. DVdm (talk) 20:30, 6 November 2010 (UTC)

Didn't we have some of this discussion re: the radial equation of planetary orbits a little more than a year ago? "Introduction to Classical Mechanics" Atam P. Arya (1990), pg 231 is a reference that explicitly connects the moving the centripetal acceleration term to the force of the equation to get the radial equation as equivalent to viewing the physics from a non-inertial frame rotating with the planet. Jeremy B. Tatum "Celestial Mechanics" Chapter 16 [2] also clearly places the radial equation in a co-rotating, non-inertial frame. --FyzixFighter (talk) 20:44, 6 November 2010 (UTC)

Ah, I see. So this is nothing new, just reopening the same old arguments interrupted only by David Tombe's ban from physics. I suggest that if David Tombe has nothing new to bring to this discussion he stops it now, especially disrupting multiple venues with the same flawed arguments, in case he attracts the same sort of attention that got him banned a year ago.--JohnBlackburne^words_deeds 20:59, 6 November 2010 (UTC)

I agree. All input from David Tombe is best ignored; it was a large part of the reason for the massive bloat in these articles and for Brews ohare's problem and eventual banning. He is well known as a physics crank, and has done nothing to move away from that position in his year off. Dicklyon (talk) 18:37, 22 December 2010 (UTC)

Dicklyon, That is quite untrue. My input to the various centrifugal force articles has been negligible, and I have consistently advocated that we only need to have one very short article. As regards the 'crank' position which are are referring to, it is very well depicted by Bond's adversary in that cartoon that you seem so keen to include in these articles. David Tombe (talk) 19:47, 14 January 2011 (UTC)

Your several hundred article edits and several hundred talk-page edits in April–July 2008 kicked off and fueled the period of Brews hyper-inflation. Dicklyon (talk) 00:12, 15 January 2011 (UTC)

In the cartoon, when 'hat guy' says, "A laughable claim, Mister Bond, perpetuated by overzealous teachers of science. Simply construct Newton's laws into a rotating system and you will see a centrifugal force term appear as plain as day," he is indeed displaying some of your confusion. In one sense, he is entirely correct: "construct Newton's laws into a rotating system and you will see a centrifugal force term appear." That's what's called a "fictitious force", and I think we all agree that it arises from a rotating reference system. On the other hand, he is probably just confused about "overzealous teachers of science," likely because he doesn't know what to make of the term "fictitious"; this is the same problem you have exhibited many times. Mr Bond is also perhaps confused when he says "there's no such things as..."; you can interpret his position as meaning that he understands that he'll be crashed by the rim of wheel accelerating him along a curved path. Perhaps it's true that these "overzealous teachers" who deny "centrifugal force" actually exist; it would be interesting to find a sourced discussion of that if so. Dicklyon (talk) 00:26, 15 January 2011 (UTC)

Dick, The centrifugal force(rotating frame of reference) perspective is certainly the most prolific in the modern literature. But it is also specialist. It is for advanced mathematicians. It is a mathematical subject about describing how things are viewed from a rotating frame of reference. It is not about physical inertia. It involves using mutually cancelling fictitious forces in relation to stationary objects which have no inertia. That is not the perspective that Bond's adversary is invoking in the cartoon. Bond's adversary is invoking real physical inertia which crushes bones. Bonds adversary is talking about coordinates fixed in a physically rotating system which induces an outward inertial force. These are two distinct ideological perspectives on centrifugal force. They both need to be treated in separate sections within a single article on centrifugal force. The two perspectives overlap in the co-rotating scenario in which case the fictitious term is describing an actual inertial force.

Mr. Bond's perspective is yet a third perspective which is popular amongst high school students. And then of course there is Isaac Newton's perspective about centrifugal force being a reaction to centripetal force. You have your opinion on which is the correct perspective, and I have mine. But both need to be represented in a single article. And at least we are both agreed that neither Newton's nor Bond's opinions are correct. It seems to be a battle over whether it is the rotating frames of reference perspective or the Leibniz perspective, with myself supporting the latter. David Tombe (talk) 00:42, 15 January 2011 (UTC)

David, you seem to have a completely different understanding of this subject from physicists. I suggest that you continue on your talk page with those interested. Martin Hogbin (talk) 02:53, 15 January 2011 (UTC)

Martin, OK. See you there. David Tombe (talk) 11:48, 15 January 2011 (UTC)

Right, except nobody is interested. I'll go back to following my advice and ignoring David. Dicklyon (talk) 05:12, 15 January 2011 (UTC)

Dick, The problem would be greatly assisted if we could actually pin you down to a definite opinion in all of this. David Tombe (talk) 11:47, 15 January 2011 (UTC)

Single Centrifugal Force Article

I am proposing that there should be a single united article on centrifugal force to cater for all the perspectives on the topic. These perspectives are,

(1) That it is a radially outward inertial force that arises in connection with absolute rotation. It obeys the inverse cube law when angular momentum is conserved, and it is observed in planetary orbits and in the centrifuge device. It does not have to be equal to a centripetal force, but in the special case when it is equal to a centripetal force, we will have circular motion. (Leibniz/Lagrangian perspective)

(2) That it is a fictitious force which shows up in the transformation equations from an inertial to a rotating frame of reference, and which is observed to act on all objects from the perspective of the rotating frame of reference, whether such objects are co-rotating or not. (modern university perspective)

(3) That centrifugal force doesn't exist, and that circular motion arises when a centripetal force deflects an object from its straight line inertial path. (modern high school perspective)

(4) That centrifugal force is an equal and opposite reaction to a centripetal force. (Isaac Newton's perspective) David Tombe (talk) 11:57, 24 January 2011 (UTC)

I think the current article does a good job of clarifying the different perspectives, this way:

(1) No sources support this perspective, so we don't mention it. The inverse cube law comes up in (2).

(2) See Centrifugal force (rotating reference frame). We have a section with a main link.

(3) I don't see why we need to represent the opinion of someone who would say that something doesn't exist, when we have reliable sources on the thing. I think this "modern high school perspective" is essentially aprochryphal anyway; or it's a confused mixup between the two concepts (2) and (4), which do exist.

(4) See Reactive centrifugal force, which is not the same thing as what is most commonly called centrifugal force, but is related. We have a section with a main link.

Further, we have a section on historical conceptions, where the relationships of different conceptions can be compared.

I think a "unified" article would be an invitation for more of David's pushing of (1), and for other bloat. I'd rather see more effort put into tuning up the articles by trimming off unneeded junk and making them clear. There is stuff worth keeping in the other articles, and too much to merge into one, I think. Dicklyon (talk) 17:27, 24 January 2011 (UTC)

Dick, As regards your claim that persepective (1) is not sourced, that is where you are absolutely wrong. I supplied some sources recently at WT:PHYS. And then you claim that centrifugal force as an inverse cube law force is dealt with in perspective (2). No it is not. It is dealt with only when studying the planetary orbital problem as per perspective (1) which you seem to be very keen to sweep under the carpet even though it is represented in your favourite cartoon. Modern textbooks which deal with perspective (2) are dealing with the rotating frame transformation equations and they never look beyond the expression mrw^2 for centrifugal force. I have never seen the inverse cube law mentioned in a chapter about rotating frames of reference. And as for your claim that the reactive centrifugal force is something different, no it isn't. In fact, strictly speaking there is no such thing as a reactive centrifugal force because it is a pro-active effect. David Tombe (talk) 18:17, 24 January 2011 (UTC)

I agree with Dick's summary of (1)-(4). We have a number of references that show that (1) is the same as (2) (see Swetz, "Learn from the Masters!", pg 269; Linton, "From Eudoxus to Einstein", pg 413; Aiton, "The celestial mechanics of Leibniz in the light of Newtonian criticism"; Arya (1990), "Introduction to Classical Mechanics" (1990), pg 231) Perspective (1) is really only interesting historically, as these references show that (1), as a study of the motion along the radius vector (Leibniz's approach), is essentially a study of motion relative to a rotating frame of reference, ie perspective (2). We also have references that (4) is something different from (2) (see Roche, "Introducing motion in a circle").

I don't know if I agree though that there is too much to merge this article and Centrifugal force (rotating reference frame). I apologize for letting the merge discussion go stale - RL issues both fun and not so fun. But I do agree that both articles need extensive trimming - maybe after the trimming it will be clearer whether the two can be merged properly or not. --FyzixFighter (talk) 19:25, 24 January 2011 (UTC)

FyzixFighter, The point which you have overlooked is that (1) and (2) are only the same in the special case when the object is co-rotating with the rotating frame of reference. What perspective (2) does is, it uses maths to patch up the difference between the real inertial effect which can be felt as an outward push on an object that is in a state of absolute rotation, and the situation where an object is sitting stationary and being observed from a rotating frame of reference. In the latter, there is no inertial effect.

Perspective (1) concentrates on the actual inertial effect which can be felt and which can break bones and doesn't have to involve a rotating frame of reference, so we can hardly say that perspective (1) and perspective (2) are the same thing. Perspective (1) does not deal with stationary objects that are being viewed from a rotating frame of reference.

Your logic basically runs like this. There is an article on equines and it doesn't mention zebras. Dick argues that zebras don't exist and that there are no sources which say that zebras exist. You argue that zebras are just a kind of horse and don't need any specific mention as they are covered under horses. And despite the fact that what you are saying is not the same as what Dick is saying, you nevertheless claim to be saying the same thing as Dick. But between the two of you, you are both trying to make sure that zebras don't get mentioned. Then when a source is produced which proves that there is such a thing as a zebra, you produce another source showing that a zebra is an equine and that therefore it doesn't need any special mention within the article. Would we really need to have a source which specifically states that a zebra is a species distinct from a horse in order to be allowed to write an article on zebras? No. But we do have sources which treat planetary orbits without mentioning rotating frames of reference and in which the centrifugal force is an outward inertial inverse cube law force. Do we need to have a special source which states that this is a different perspective on centrifugal force from the perspective which ascribes a centrifugal force to a stationary object which doesn't actually possess any inertia and which merely appears to move in a circle? David Tombe (talk) 20:08, 24 January 2011 (UTC)

David, it is quite simple. You are wrong. Your argument is based on a bizarre conspiracy theory of physicists. This shows that not only do you not understand physics but you do not understand conspiracy theories. It is time to call it a day. Martin Hogbin (talk) 20:14, 24 January 2011 (UTC)

Martin, Which conspiracy theory are you talking about? Can you not see the difference between,

(a) An object with an absolute angular momentum that is pushing outwards from a centre due to its inertia, and

(b) An object that is sitting stationary with no inertia, but which is being observed to move in a circle from the perspective of somebody in a rotating frame of reference?

Those are two different physical situations. Can you not see the difference between them? Only situation (a) involves an inertial centrifugal force. I know that you think that situation (b) involves a centrifugal force and a radially inward Coriolis force, but this is just mathematical accountancy and doesn't involve any real inertial effects as such. David Tombe (talk) 20:24, 24 January 2011 (UTC)

@David - since we do have multiple reliable sources that say (1) is understood today as a specific application of the more general (2), then yes, we do need a reliable source that says (1) and (2) are distinct. Please remember WP:OR, WP:FRINGE, WP:BATTLE, and WP:SOAP, which you have previously been warned about. --FyzixFighter (talk) 20:43, 24 January 2011 (UTC)

FyzixFighter, There is a completely different emphasis. Perspective (1) is about actual motion along the radial vector. It's about actual inertia. It about a force which can be felt. Perspective (2) is about accounting for observations from a rotating frame of reference and it applies centrifugal force to situations in which there is no actual inertia. They are completely different perspectives on the subject, and I can show you multiple sources that deal with the orbital problem without using a rotating frame of reference. David Tombe (talk) 21:12, 24 January 2011 (UTC)

The merge proposed in its current form runs the risk of violating WP:SYNTHESIS. If each of the perspectives are so different, why is a joint article preferable? To justify a single article about all the perspectives listed, we would need a single source covering them all, as opposed to lots of sources each discussing one perspective. Details on each perspective could be filled in using other sources, but without the overarching source we wouldn't actually have any evidence that there is a single topic to cover. Alzarian16 (talk) 10:05, 25 January 2011 (UTC)

Confusion with Centripetal Force

Without a doubt, many people come to this page to understand the difference between centripetal and centrifugal force. The current explanation, while correct, is only understandable to people who already understand these concepts. Here are two external articles that do a significantly better job: physlink.com and www.suite101.com/content/centripetal-vs-centrifugal-a15865 (can't link directly because of a spam filter, but the article is good). —Preceding unsigned comment added by 90.231.129.170 (talk) 01:52, 28 January 2011 (UTC)

Anon 90.231.129.170, It's a pity that such confusion should exist between two quite different concepts, particularly when the very etymologies of the two words mean that one is an inward acting force whereas that other is an outward acting force. And alot of that confusion is down to Isaac Newton. Have a look at this very interesting web link [3] which explains Newton's reaction to Leibniz's views on centrifugal force.

The two web links which you have provided are very much based on the Newtonian concept of centrifugal force being an equal and opposite reaction to centripetal force. But the truth is that centrifugal force is a pro-active inverse cube law force which is not in general equal in magnitude to the centripetal force. It is generally agreed nowadays that even in the special case of circular motion, where the centripetal force will indeed be equal in magnitude to the centrifugal force, that the two will not form an action-reaction pair. Also, in case you are in any doubt as to whether or not centrifugal force is a reactive force or a pro-active force, then consider the simple case of a weight being swung on the end of a string in a horizontal plane. The centripetal force is caused by the tension in the string. But that tension is first of all caused by the tendency of the weight to move in a straight line, which in turn causes the radially outward inertial effect. The inward centripetal force doesn't kick in until the centrifugal force is already established. David Tombe (talk) 17:04, 28 January 2011 (UTC)

Nonsense. Dicklyon (talk) 00:01, 29 January 2011 (UTC)

This does indeed seem nonsense. Yoenit (talk) 00:20, 29 January 2011 (UTC)