Wikipedia:Featured picture candidates/Foucault Pendulum

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[edit] Foucault Pendulum

Original - Animation of a Foucault pendulum showing the sense of rotation on the southern hemisphere. The rate of rotation is greatly exaggerated. A real Foucault pendulum, released from rest, does not pass directly over its equilibrium position as the one in the animation does.

Reason

I happened across this entirely by accident when I went to the signpost page to determine why it was linked to an open afd of mine. While there I caught sight of the 2007 picture of the year link, and the image caught my eye. Its a finalist from the competition, and is already featured on the commons.

Articles this image appears in

Universe, Foucault pendulum

Creator

Commons User:DemonDeLuxe

• Support as nominator TomStar81 (Talk) 04:33, 27 January 2008 (UTC)
• Support Durova^Charge! 05:35, 27 January 2008 (UTC)
• Support - Alvesgaspar (talk) 09:17, 27 January 2008 (UTC)
• Comment - it's a brilliant animation, but with a few problems. If it's greatly exaggerated motion, and "A real Foucault pendulum, released from rest, does not pass directly over its equilibrium position as the one in the animation does", why are we featuring it? It's factually inaccurate, and without an accompanying caption/article, is misleading. Also, what's the consensus over FPing this version with a German compass rose (O for Ost as opposed to East)? —Vanderdecken∴ ∫ξφ 09:44, 27 January 2008 (UTC)
• Oppose per Vanderdecken. I will happily support a corrected version.--HereToHelp ^{(talk to me)} 14:34, 27 January 2008 (UTC)
• Oppose per Vanderdecken. Also the reflection of the ball on the photo is distracting. de Bivort 15:52, 27 January 2008 (UTC)
• Oppose. A real Foucault Pendulum takes 24 hours to complete the oscillation cycle-- this is misleading and therefore unencyclopedic. Spikebrennan (talk) 23:54, 27 January 2008 (UTC)

• I believe the point here is not to show the time, but the trajectory of the pendulum. Surely an animated gif which takes 24 hours to complete its purpose wouldn't be of much encyclopedic value. I think a simple caption will take care of the time paradox, but as stated by Vanderdecken, the fact that the caption has excuse the pendulum's path of moving over the equilibrium makes this one a reach for me. —DMCer™ 12:34, 30 January 2008 (UTC)

Comment It is plain nonsense that the pendulum takes 24 hours to go all the way around. It is 24h / sin |latitude|. That is, it is only at the poles it takes 24 hours. At the equator it does not go around at all. In between it is more than 24 hours. If you were to add a watch it would then have to be localized to a specific latitude. -- Slaunger (talk) 16:41, 2 February 2008 (UTC)

• Weak Oppose as per factual inaccuracy stated by Venderdecken and irritating rear reflection. On a side note, however, I think it does a great service for the Graphics Interchange Format. -- Altiris Helios Exeunt 08:28, 28 January 2008 (UTC)
  • Would you support a slower version? Or one with a timer shown? I don't think making it literally 24 hours is a good idea but removing the illusion of such speed might be. gren グレン 08:30, 28 January 2008 (UTC)
    • Stick a clock on the wall next to the picture with only an hour hand. —Vanderdecken∴ ∫ξφ 12:02, 28 January 2008 (UTC)
      • That still wouldn't help. The plane of a Foucault pendulum's oscillation, in New York City for example, rotates 235 degrees in a day, but it would oscillate back and forth hundreds of times (exact number would depend on the length of the pendulum). The only way to make it accurate in both its rate of oscillation and rotation would be for the diagram to simulate the movements of such a pendulum in a planet with profoundly weak gravity - and then speed up the animation relative to actual time. Meniscus (talk) 00:11, 31 January 2008 (UTC)
        • Couldn't we just say this is the theoretical perfection of the oscillation? Obviously in planetary physics and such you will very rarely run across an example that doesn't have some sort of variable messing it up. Couldn't we just rewrite the caption to reflect that? Clegs (talk) 03:42, 1 February 2008 (UTC)
• Comments Can not believe this was a finalist for PoTY at commons. Wikipedia sure is tough to please :D --Muhammad(talk) 19:19, 1 February 2008 (UTC)

• I believe the difference is probably because Commons is primarily concerned with the artistic value (which is very high here, it's a gorgeous animation) and Wikipedia is primarily concerned with encyclopedic value (which is small here because of several factual errors). Clegs (talk) 20:33, 1 February 2008 (UTC)

• Comment Regarding Vanderdeckens comment that the Foucault pendulum does not pass through the center when released from rest in the rotating coordinate system that is correct. But the pendulum does not have to be released that way! The animation actually depicts the trajectory as seen from the rotating system when released from rest in an inertial system. This can easily be accomplished in the rotating frame by giving it a small initial tangential velocity when released. Concerning that the animation is misleading, I think it would be nonsense to animate it in real time. It can be correct by the way if the pendulum is suspended in a very very long line as the period of oscillation goes up that way. -- Slaunger (talk) 16:37, 2 February 2008 (UTC)
• Support As explained above it is the caption, which is misleading. The animation can be correct concerning the trajectory. It is a matter of the initial boundary conditions of the equations of motion. And concerning the exaggerated angular velocity it has to be this way to illustrate the motion. A clock won't do as the clock depends on the latitude. -- Slaunger (talk) 19:26, 2 February 2008 (UTC)
  • Comment I think the solution to making this an encyclopedic picture is to have a caption that includes the characteristics of the planet it is operating on. For instance, this image would work on a planet if we say that the pendulum is located at the north pole (the rotation would be opposite on the south pole) of a planet with earths gravity, except with a rotational rate ~10,000 times faster than Earth's. To get this factor exactly we need someone to measure the exact time it takes this animation to repeat itself and then divide the length of a sidereal day on Earth by this time. The result would give how much faster a planet would have to be rotating than Earth for this animation to be accurate at its north pole. Without the relevant planetary statistics I would have to oppose this image based on its unencyclopedic nature. Meniscus (talk) 16:11, 3 February 2008 (UTC)
• Oppose per others. As such, it is misleading, doesn't represent the "traditional" pendulum experiment. --Janke | Talk 17:33, 3 February 2008 (UTC)

Not promoted MER-C 04:29, 4 February 2008 (UTC)