Brachistochrone problem. The classical problem in calculus of variation is the so called brachistochrone problem1 posed (and solved) by Bernoulli in The brachistochrone problem asks us to find the “curve of quickest descent,” and so it would be particularly fitting to have the quickest possible solution. THE BRACHISTOCHRONE PROBLEM. Imagine a metal bead with a wire threaded through a hole in it, so that the bead can slide with no friction along the .

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From Wikipedia, the free encyclopedia. Tautochrone Problem Ed Pegg Jr. Joseph-Louis Lagrange did further work that resulted in modern infinitesimal calculus.

The method is to determine the curvature of the curve at brcahistochrone point.

A body is regarded as sliding along any small circular arc Ce between the radii KC and Ke, with centre K fixed. Note, that eL is not the tangent at e, and that o will be negative when L is between B and E.

Brachistochrone Problem

Retrieved 2 June A History of Mathematics, 2nd ed. Either Gregory did not understand Newton’s argument, or Newton’s explanation was very brief. Brachistochrone Problem Okay Arik. Assuming now that Fig.

Brachistochrone Problem — from Wolfram MathWorld

Bernoulli, writing to Henri Basnage in Marchrecognised that although the author, “by an excess of modesty” had not revealed his name, yet even from the scant details supplied he knew that it was from Mr Newton, “as the lion by its claw”. After deriving the differential equation for the curve by the method given below, he went on to show that it does yield a cycloid. Clearly there has to be 2 equal and opposite displacements, or the body would not return to the endpoint, A, of the curve.


Following advice from Leibniz, he only included the indirect method in the Acta Eruditorum Lipsidae of May From this the equation of the curve could be obtained from the integral calculus, though he does not demonstrate this. Wikimedia Commons has media related to Brachistochrone.

Assume AMmB is the part of the cycloid joining A to B, which the body slides down in the minimum time.

He explained that he had not published it infor reasons which no longer applied in He does not explain that because Mm is so small the speed along it can be assumed to be the speed at M, which is as the square root of MD, the vertical distance of M below the horizontal line AL. From a property of the cycloid, En is the normal to the tangent at E, and similarly the tangent at E is parallel to VH. Teacher 60, A History of Mathematics: Both solutions appeared anonymously in Philosophical Transactions of the Royal Society, for January Hints help you try the next step on your own.


To proceed, one would normally have to apply the full-blown Euler-Lagrange differential equation.

By the conservation of energythe instantaneous speed of a body v after falling a height y in a uniform gravitational field is given by:. At the request of Leibniz, the time was publicly extended for a year and a half.

Brachistochrone problem

The circular arc through C with centre K is Ce. Johann and his brother Jakob Bernoulli derived the same solution, but Johann’s derivation was incorrect, and he tried to pass off Jakob’s solution as his own.

Marchione Hospitalio communicatarum solutionum problematis curva celerrimi prroblem a Dn. Point D on AL is vertically above M.

The brachistochrone problem

In that case, terms corresponding to the normal component of weight and the normal component of the acceleration present because of path curvature must be included. Now consider the changes along the two neighboring paths in the figure below for which the brachistochorne separation between paths along the central grachistochrone is d 2 x the same for both the upper and lower differential triangles.

This property, which Bernoulli says had been known for a long time, is unique to the cycloid.