Sphere in a cone (ball in a wine glass)

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The discussion focuses on determining the optimal radius R of a sphere that maximizes volume displacement when placed inside a cone with height H and angle A. The approach involves reducing the problem to a two-dimensional case by utilizing the cone's rotational symmetry. Participants suggest deriving the cone's equation based on angle A, formulating the equation for the circumscribed circle of radius R, and then applying integral calculus to find the maximum displacement by differentiating with respect to R and setting the result to zero.

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sphere in a cone (ball in a martini glass)

A problem a friend mentioned to me years ago.

You have a cone with height H and angle A. What is the radius R of a sphere that when placed in the cone, displaces the most volume?

One suggestion was to reduce this to a two dimensional case.
 
Last edited:
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Yeah, rotational symmetry would allow reduction to the 2-d case; so, set it up: what's the equation of a cone of angle A? the equation of the circle of radius R circumscribed therein? do the integral, get it in terms of R, differentiate w.r.t. R and set equal to 0.
 
Correction: ball in a martini glass.

Glad I could help.
 

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