Talk:Foucault pendulum

message: Interestingly, although the article states that "When a Foucault pendulum is suspended on the equator, the plane of oscillation remains fixed relative to Earth." this has never been tested - perhaps not unsurprisingly..... Thomas Goodey
There should be more info please???????
* If you understand the situation at a pole: the Earth is rotating but not the plane of oscillations which is fixed to stars and not Earth, you could understand the situation at the equator. Earth is not rotating around a vertical axis at the equator. If you look at the stars at the equator, they do not draw circles but lines, but at the pole they are circling. More precisely, if at the pole, you were following a specific star, the trajectory of this specific star will be a single point but the trajectories of some stars around it are circles which will not end in one day but in a longer time which depends on how high was your chosen fixed star in the sky. If the angle is 90 degrees, you will find the Polar star and the stars around will circle in 24 hours, but if your angle is 48 degrees like in Paris and find a star at that angle and follow it, the stars around it will circle in 24/sin(48°). And if you find a star at the horizon, stars around it will not circle at all. This is what happens will the Foucault pendulum. Hope that helps you.--Nbrouard (talk) 15:19, 14 February 2015 (UTC)
thread_title: Pendulum on the Equator

message: A recent BBC news article about eclipses had the following quote:
That looks like something which should be verified and added to the article?
--.../Nemo (talk) 00:05, 22 May 2008 (UTC)
replies: text: I have come across references to reports of anomalies in Foucault pendulum motion during eclipses. It is my understanding that the magnitude of the anomalies was so small that it is very difficult to distinguish them from the various perturbing influences that make a Foucault pendulum deviate from the motion predicted by the mathematical models. So for one thing it is not certain that the described anomalies cannot be accounted for in terms of known perturbative factors. Since solar eclipses are very rare and are very short in duration, it's very difficult to set up an experiment. In my opinion the 'anomalies during eclipses' story doesn't merit inclusion in the wikipedia article. --Cleonis | Talk 21:54, 22 May 2008 (UTC)
replies: text:  It's called the Allais effect.  It's a bunch of crap, which is why, when I suggested it be mentioned here, it was decided to leave it out.Rracecarr (talk) 03:08, 10 July 2008 (UTC)
replies: text:  Isn't the cause just the draught of all the people rushing outside to see the eclipse?  Dbfirs 22:08, 9 February 2010 (UTC)
thread_title:  eclipses 

message: I'm wondering if anybody knows anything specifically about the pendulum in the Paris pantheon.  How does it keep moving?  69.220.2.188 (talk) 01:36, 10 July 2008 (UTC)
replies: text: Please have a look at the Fernand Charron's annular (1931) in the French wikipedia. It has been used at the Palais de la Découverte's pendulum in Paris for a while. Now, and for most recent pendulums, there is probably something different.--Nbrouard (talk) 14:25, 20 November 2008 (UTC)
thread_title:  Pantheon Pendulum 

message: Hi Nbrouard,
in the previous sections I already gave some reasons for being dissatisfied with the gnuplot animations. 
The original is 640x480 pixels. The lines in that animation are single pixel lines. 
In the article the code specifies a width of 250px. But downscaling an animation is a horrible waste of resources: each frame of the animation must be scaled down individually! And this entire downscaling must be performed again and again, each time the page is viewed.
An animation must always be displayed in original resolution. If a animation must be small then it must be manufactured and uploaded in the intended resolution.
It seems to me that animation is too limited to explain the physics. 
Some months ago I created two Java simulations, using EJS, a tool for generating simulations complete with user interface. 
These Java simulations are available on two locations: my own website, and in the Open Source Physics repository of featured simulations. I give the links to the OSP pages. 
- Circumnavigating pendulum: a 2D simulation that focuses on an essential aspect of the Foucault pendulum motion. 
- Foucault pendulum: a full 3D simulation of the Foucault effect.
The simulations calculate the trajectories by performing numerical analysis of the differential equations.
It is difficult to see how the information that is conveyed by those applets is to be conveyed in an animation. 
I have created animations with POV-ray, such as the animations for the Coriolis flow meter article. I can try to create something similar to the animation that DemondeLuxe created, but with cusps (but to save KB's I would use a palet of 16 shades of grey instead of full color) --Cleonis | Talk 23:11, 27 March 2009 (UTC)
thread_title:  The gnuplot animation 

message: Currently, the article states: "Air resistance damps the oscillation, so Foucault pendulums in museums often incorporate an electromagnetic or other drive to keep the bob swinging; others are restarted regularly."
What about friction at the pivot point? Doesn't that dampen the oscillation, too? Freddicus (talk) 21:46, 9 February 2010 (UTC)
replies: text: Yes, there is a small amount of friction (and movement) at the pivot, but the energy lost at a well-designed and firmly-supported pivot is small compared to that lost through the effects of air resistance.  Dbfirs 22:01, 9 February 2010 (UTC)
replies: text: Thanks, I didn't know that! Is it worth mentioning what you just said in the article? Freddicus (talk) 16:06, 11 February 2010 (UTC)
thread_title:  Oscillation dampened by friction? 

message: I noticed the lead length tag at the top of the page, so I extended it just a bit; I didn't feel there was much to summarize without repeating information. What do you folks think? Somnambulent (talk) 16:44, 29 November 2010 (UTC)
thread_title:  Lead paragraph 

message: This section is complete bogus. Firstly, it's just a bunch of loosely knitted heuristic arguments with little value of actually explaining anything. They are so vague that it's basically impossible to assess if they are right or not, or where they go wrong. More importantly, the only clearly stated point "The apparent rotation of Foucault's pendulum is not due to the Coriolis Effect" is plain wrong. The Foucault rotation can be explained in a number of ways, and the Coriolis effect is one of them. It arises if one chooses the rotating frame of reference given by an earthbound observer, and one considers the corresponding equations of motions. This is explicitly done two sections higher and the calculations clearly show that the term corresponding to the Coriolis force is responsible for the Foucault rotation.  
If one chooses an inertial system as a reference system, there is of course no Coriolis force, so from that perspective other effects are responsible. This leads to the "parallel transport" interpretation. If the calculation for parallel transport is carried out in local coordinates given by latitude and longitude the Coriolis force reappears as the Christoffel symbols.
I am removing the section, don't put it back in before actually doing a calculation yourself.
ShanRen (talk) 19:51, 15 April 2011 (UTC)
thread_title:  Re: Visualization: Foucault vs. Coriolis   

message: The reason the actions of the Foucault pendulum took a long time to be noticed is that the way the pendulum is fastened to its anchorage up top has got to enable free movement over planes of swing of 360 degrees of play. A stone wrapped in a rope tied to a tree limb will lose the effect due to friction in the rope and the knot up top. Thus, the whole key to such a pendulum is the linkage that goes up top. I turned to this page to see the drawing that has appeared at the pendulums in museums that I have seen, but it isn't here. 4.154.253.192 (talk) 21:33, 20 June 2011 (UTC)
replies: text: What kind of linkage are you thinking of? It should suffice if the wire is just made to pass tightly through a rigidly-clamped pinhole-aperture. That will prevent the asymmetric friction which you describe. (You could also add a fishing line swivel, if you were concerned with minimising oscillating twisting/torsion, but that would be unlikely to affect the pendulum operation.) Cesiumfrog (talk) 04:09, 16 August 2011 (UTC)
thread_title:  Where's the linkage? 

message: Did the South Pole pendulum rotate with a periond of 24 hrs or a period of 23.93 hrs?
see http://en.wikipedia.org/wiki/Foucault_pendulum#Foucault_pendulums_around_the_world
D c weber (talk) 17:13, 20 December 2012 (UTC)
thread_title:  Was the South Pole pendulum asiderial day period? 

message: Why is the first section heading, "Original Foucault pendulum", in italics?--Rockfang (talk) 06:17, 18 September 2013 (UTC)
thread_title:  First section heading in italics 

message: The last paragraph seems strikingly out of keeping with the rest of the article. Could someone familiar with the article take a look? The paragraph needs a little copyediting, but most of all, what's with the editorializing statement Therefore, they were compelled to complete this tribute to science? The therefore makes no sense, as the statement isn't drawing a logical conclusion from what came before. Sounds a bit like an auto-translation. The paragraph also has no citation. Cynwolfe (talk) 12:32, 18 September 2013 (UTC)
thread_title:  Last paragraph needs a look 

message: *The article says that The plane of the pendulum's swing rotated clockwise 11° per hour, making a full circle in 32.7 hours
and it also says that For example, a Foucault pendulum at 30° south latitude, viewed from above by an earthbound observer, rotates counterclockwise 360° in two days.
Neither of the two sentences is right. The article should indicate:
*The center of circle on which is moving the pendulum moves to the right 15º per hour (in the Northern Hemisphere) since it is located on a parallel of latitude which gives a complete dayly turn in 24 hours. As a consequence, any point on that circle will turn twice everyday: one turn around the parallel of latitude and another turn around the center of the same circle. If movement of pendulum throw 24 pins around the circle (15º distance from one another), all of them will fall in 12 hours: 12 pins each half circle. Pins are displaced by pendulum to the left, that is, counterclockwise, on the Northern hemisphere (in both ways) and  to the right (clockwise) in the souther hemisphere, also in both ways. --Fev (talk) • (contribs)  —Preceding undated comment added 03:47, 7 February 2014 (UTC)
replies: text: Are you sure that the confusion is not yours?  Have you checked your facts with scientific papers?  Dbfirs 09:29, 7 February 2014 (UTC)
thread_title:  BIG confusion in this article 

message: To explain the behaviour of the Foucault pendulum there is no need to introduce and analyze mysterious fictitious forces : one must only observe that during a time interval as short as you like, the swinging plane's direction can be considered fixed relatively to the stars, but its trace on the observation table moves because that table and thus the South engraved mark rotates (in absolute space) under the pendulum with the constant angular speed (ω sinλ) around the instantaneous but mobile position of the vertical n(t) at the location of the pendulum. In the northern hemisphere the South mark rotates (unseen by the Earthbound observer) counterclockwise, while during a short time span the pendulum trace stays stationary in absolute space. Thus the Earthbound observer sees the trace moving clockwise with the above mentioned angular speed. And what is important to note is the fact that in his Earthbound reference system these angular variations can be arithmetically added, that is integrated. Thus the Foucault pendulum law is explained (of course I exclude here the more sophisticated elliptic moves). One must add that the curvatures of the trace seen in the animations are enormously exxagerated. By the way a strictly plane trajectory in absolute space is necessarily curved in the rotating system. Chessfan (talk) 10:11, 13 February 2014 (UTC)
thread_title:  A very simple geometric demonstration 

message: According the given formula, the numbers for rotation rate (in degrees per hour) and precession period (in days) are now accurate to one decimal place.  The previous version seems to have calculated the rotation rate to the nearest degree, and then introduced some roundoff error by using that value to compute the period.  Of course, it would be better to use an original measurement instead of a computed ideal value, but it is what it is for now.  Deacon Vorbis (talk) 03:34, 9 February 2017 (UTC)
thread_title:  Some data 

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thread_title:  External links modified 

message: An extended version - of course not for implementing  -  only for executing the jus primae censurae delentis - the most exciting zest of Wikipedia upper class great-authors.--Modalanalytiker (talk) 12:33, 29 December 2018 (UTC)
thread_title:  New version 

message: https://www.youtube.com/watch?v=YjP-MLXdGYY
has a 12 hour video showing the Foucault rotation of a 1 meter driven pendulum.  That page also has links to pages showing how it is built, and a variation on the explanation of the rotation.  I would appreciate it if a link could be added to this page.
John Dooley 2601:985:104:4470:14B0:697F:5CDA:5BFE (talk) jwdooley@aol.com  — Preceding undated comment added 21:37, 18 December 2020 (UTC)
thread_title:  1 meter foucault pendulum video and how-to 

message: It is said that a Foucault pendulum is not restricted to remain in a single defined linear direction or it can swing in any direction in the vertical. Earth’s rotation can’t force the bob to swivel therefore let the Foucault pendulum be at rest instead of swinging back and forth.  
Attached or fixed the laser pointer to the great circle of the bob of the said pendulum. The laser beam shines perpendicular to the suspend wire of the pendulum. Earth rotates beneath the bob when the Foucault pendulum is at rest as there is a relative motion exist between them. This means the laser shines in a specific direction in a fixed plane while the earth and the building the pendulum resides rotates about the said plane in which a bob rest. Even a simple mark on the aforementioned bob (not on points through which its mg is passed) is enough to notice the rotation of the earth with the passage of time.39.32.106.21 (talk) 10:10, 30 April 2021 (UTC)
thread_title:  Does swing really matter when a similar result is obtained from a static Foucault pendulum?  

message: I have several problems with this page,
This needs to be said before the first example, not afterwards. "the amount of time that it takes for the pendulum to make one full rotation (with respect to its surroundings) is equal to one sidereal day (23.93 hours) divided by the sine of the latitude of its location. When a Foucault pendulum is suspended at the equator, the plane of oscillation remains fixed relative to Earth. At other latitudes, the plane of oscillation precesses relative to Earth, but more slowly than at the pole, proportional to the sine of the latitude..."
Secondly, people aren't content with amateur footage of the Parthenon? We might need a twelve hour video to explain precession?
There are several far more useful depictions on the wiki commons page.
https://commons.wikimedia.org/wiki/Category:Foucault_pendulums
I humbly request this page gets submitted to an authority that will rigorously edit this page.
This surely has to one of the most well known scientific examples of the heliocentric universe. And it seems impossible to read by the average reader, and the simple Wikipedia offers no explanation. 49.185.200.59 (talk) 04:16, 18 May 2022 (UTC)
replies: text: There is no authority.  Why don't you try implementing the changes you describe? WP:BEBOLD CyreJ (talk) 06:48, 18 May 2022 (UTC)
thread_title:  Wherever you put it, Foucault's Pendulum swings from a motionless point while the earth rotates beneath it. Every point of the universe is a fixed point: all you have to do is hang the Pendulum from it 

message: The second section of the article ("Original Foucault pendulum") uses \phi for the latitude variable, but the remainder of the article after that uses \varphi. Are these representing the same quantity? If so, I suggest they should use the same variable. Is there a typical choice for this variable name in the literature? The Latitude article seems to use \phi. —⁠ ⁠BarrelProof (talk) 22:34, 25 September 2022 (UTC)
thread_title:  Choice of latitude variable 

message: In article "rotating clockwise approximately 11.3° per hour." - is this correct?  — Preceding unsigned comment added by 146.66.167.197 (talk) 05:36, 25 November 2022 (UTC)
replies: text: Yes, in the northern hemisphere the pendulum swings clockwise. Nbrouard (talk) 19:04, 25 November 2022 (UTC)
thread_title:  Clockwise vs Counter clockwise 

message: if the oscillations could be perpetuated for twenty-four hours, the trace of their plane would then execute an entire revolution  Then the article describes how, except at the poles, the pendulum executes only part of a revolution in 24 hours.
Did Foucalt get this wrong? Is the restriction missing by selective quotation?  It seems to be misleading, and contrary and confusing. Without qualification, it's a bad place to start. 1.159.36.184 (talk) 11:07, 28 June 2023 (UTC)
replies: text: The pendulum is at the North Pole. Before the quote, Foucault wrote "l’observateur se transporte au pôle pour y établir un pendule réduit à sa plus grande simplicité". Ceinturion (talk) 14:32, 28 June 2023 (UTC)
thread_title:  "perpetuated for twenty-four hours ... an entire revolution" 

message: I understand that picture "Foucault pendulum animated" is not real but it is misleading from my point of view. Pendulum doesn't move so fast in real observation, changes of direction are much smaller... 213.29.28.253 (talk) 09:18, 5 May 2024 (UTC)
replies: text: My note was about :File:Foucault pendulum animated.gif. The real observation is much different... 213.29.28.253 (talk) 22:07, 7 May 2024 (UTC)
thread_title:  Animated picture Foucault pendulum animated is misleading