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Old 27-02-2011, 07:28 AM
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sjastro
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Quote:
Originally Posted by mithrandir View Post
I think you will find that the vertical wire is the limit case of the brachistochrone when the points become vertically aligned. I don't feel up to remembering enough of my Calculus of Variations course - more than 30 years ago - to prove it.

Andrew
What you will find is that the partial derivatives in Euler LaGrange equation vanish as there is no horizontal component. This reduces the equation to the trivial case 0=0. There is no stationary value.

From a physics perspective since the wire is frictionless, the wire does not provide a constraint when the endpoints are vertical. The bead falls purely under the effect of gravity which is in a straight line.

Regards

Steven
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