Talk:Spherical pendulum
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Illustration inconsistant with text?
editThe text has the location as (r, theta, phi), but there's no 'r' in the illustration, it's 'l'. Am I missing something? Does anyone know if there's a standard nomenclature for this? Should the label be changed or the text? A2800276 (talk) 15:25, 8 May 2016 (UTC)
- The r is part of the spherical coordinate system, l is the constant length of the pendulum. For solving the problem just take r = l. M∧Ŝc2ħεИτlk 15:48, 8 May 2016 (UTC)
Yeah, I realize that, but you don't feel it's confusing to have two very closely related concepts ("l" and "r") that are in fact equal and use one in the text and the other in the illustration and not make any mention of the fact? A2800276 (talk) 21:28, 8 May 2016 (UTC)
Strike that, it has been corrected :) A2800276 (talk) 21:29, 8 May 2016 (UTC)
Aka conical pendulum?
editIs this the same as conical pendulum? 24.241.226.16 07:43, 16 October 2006 (UTC)
No, that's a special case, though. 72.166.213.249 14:24, 5 March 2007 (UTC)
No, i think the other way round, because a ball in a spherical bowl can roll, but a ball swinging on a rope cannot.
You find the answers on p.33/34 of the reference that is now given.
—Preceding unsigned comment added by 193.175.73.207 (talk) 08:38, 29 May 2009 (UTC)
Euler-Lagrange Equation
editI was the Last guy to fix the E-L equation, but I think we need to put a diffrent version of it because of all the fixes it has been through. If a lot of people argue about the same sign, maybe we should just change the equation so that it won't confuse people anymore. — Preceding unsigned comment added by 94.159.230.164 (talk) 16:13, 8 October 2012 (UTC)
- the sign here is wrong, if theta is taken as the one in the (r,theta,phi), there should be a minus in the lagrangian. by what is written, the potential energy is -mgr*cos(theta). then, if theta equals 0, since the axis is taken from the fixed point of the string, the energy at the highest point, which is in the upper half of z axis, is -mgr, and there shouldn't be a minus there. if theta is taken from -z and not z, then the equation is ok. — Preceding unsigned comment added by 132.72.225.222 (talk) 00:03, 6 November 2013 (UTC)