Talk:Foucault pendulum/Archive 1

message: I suggest removing the link: 
*"About Foucault pendulums". California Academy of Sciences, 2003.
from the External links section.
The cartoons are gorgeous, but the site presents misleading and wrong information. On the third page two questions about the world are confused. Whether the Earth is flat, and whether the Earth is rotating. 
In the community of greek scholars, there was consensus that the Earth is a sphere, since the greek scholars were aware of convincing evidence that the Earth is spherical. All through the centuries it has been recognized by scholars that given the evidence it is clear that the Earth is spherical in shape. 
(The american writer Washington Irving concocted the myth that during the middle Ages European scholars believed the Earth to be flat. Unfortunately this myth, started in 1826, is still widespread.) 
It is impossible to see whether the Earth is rotating. It was assumed that the Earth is statonary, because given the knowledge available at the time there were compelling reasons to do so.
On the seventh page it is stated:<BR>
:Note that while the Pendulum seems to change its path during the day -- actually it is the floor beneath it that changes, being twisted around by the daily rotation of earth.
This statement is wrong. At latitudes away from the Poles and the Equator the plane of oscillation of the pendulum is rotating both with respect to the Earth and with respect to the stars. <BR>
--Cleon Teunissen | Talk 08:47, 21 July 2005 (UTC)
thread_title:  The California Academy of Sciences 

message: * Durran, D. R., 1993: Is the Coriolis force really responsible for the inertial oscillation?, Bull. Amer. Meteor. Soc., 74, 2179–2184;  Corrigenda. Bulletin of the  American Meteorological Society, 75, 261 
* Persson, A.
** How do we Understand the Coriolis Force? Bulletin of the American Meteorological Society 79, 1998, 1373-1385. 
** The Coriolis Effect: Four centuries of conflict between common sense and mathematics, Part I: A history to 1885 History of Meteorology 2 (2005)
* Norman A. Phillips
**An Explication of the Coriolis Effect, Bulletin of the American Meteorological Society: Vol. 81, No. 2, 2000, pp. 299–303. 
**What Makes the Foucault Pendulum Move among the Stars? Science and Education, Volume 13, Number 7, November 2004, pp. 653-661(9)
Specifically, the Bulletin of the Americal Meteorological Society (BAMS) and the Meteohistory.org site count as peer-reviewed journals. You should not oppose information that comes from articles that have passed the rigours of getting it published in a peer-reviewed journal. 
If you do a google search of the respective authors, you will find they are well respected experts in the field of metorology, specialized in the mathematics of modeling the motions of air over the Earth. Understanding the mechanics of the coriolis effect is the very core of their expertise. --Cleonis | Talk 06:25, 3 May 2006 (UTC)
thread_title:  References for the Foucault pendulum article 

message: I have reverted a diagram being replaced with an animation.
The animation: :Image:Foucault pendulum animated.gif is correct for the following situation: A foucault pendulum located on the southern hemisphere that swings so slowly that it takes 24 hours to complete 8 swings.
The diagram that I made :Image:Foucault pendulum precession2.png is strictly speaking physically unrealistic: my diagram shows on one hand the 'spikyness' that applies in the case of a Foucault pendulum performing thousands of swings in 24 hours. On the other hand, my diagram shows a large angle from one swing to the next, which physically corresponds to the case of a pendulum that swings in the order of ten times in 24 hours.
Strictly speaking, my diagram is a hybrid, moving away from what is physically realistic in order to bring particular features more into focus.  
Actual Foucault pendulums swing thousands of times in 24 hours. Clearly, it is not possible to produce a transparent diagram or animation that remains true to that.
In Alonso and Finn Fundamental University Physics (second edition) Volume 1, section 6.4 (page 121), the diagram representing the swing of Foucault pendulum is the same as my diagram. Evidently Alonso and Finn opted for the same compromise: the spikyness at the extremes is retained, only the amount of curving to the right (on the northern hemisphere) is exaggerated. --Cleonis | Talk 14:56, 11 September 2006 (UTC)
thread_title:  The spikyness of the extremes of the swing 

message: In his demonstration in the Pantheon, Foucault used a method of release that was technically good as well as theatrical: he would pull the pendulum to the side with a thin cord, wait until any rocking and swinging of the pendulum had subsided, and then he burned the cord. 
Let a very long Foucault pendulum be located exactly above the geometric south pole. Assume that the pendulum is a perfect pendulum. With this south pole pendulum the same release method is used as was used by Foucault. After being released in this way, the trajectory of the pendulum bob with respect to inertial space is not planar, it is an ellipse with one axis much longer than the other. The long axis is the swing of the pendulum between its outermost points. The non-zero-ness of the short axis is due to the fact that a an object that is stationary with respect to the Earth, has a tangential velocity with respect to the Earth's axis.
By contrast, in order for the pendulum swing to be planar with respect to inertial space, the release mechanism must compensate for the rotation of the Earth. This can be achieved with a mechanism similar to what is used for telescopes: motors and gears in the supporting rig make the telescope rotate with respect to the Earth in such a way that the telescope remains pointing at the same star.
The release method that Foucault used does not impart a pure planar swing to the pendulum bob. The animation :Image:Foucault pendulum animated.gif is based on assuming a swing that is planar with respect to inertial space. --Cleonis | Talk 15:29, 11 September 2006 (UTC)
thread_title:  Dependence on how the pendulum bob is released.