This business of weird rolling shapes got me musing. One could design a "ball" that, released from rest in the proper orientation on a sufficiently flat surface, would roll along a predetermined path. In principle, if one were parsimonious enough with potential energy, the path could be arbitrarily ornate, though the object would roll very slowly along it. So, in practice, how complicated a path could be programmed into, say, a machined steel roller? Could a skilled machinist create a "signature" roller that wrote the machinist's name? On Thu, Apr 22, 2010 at 2:38 PM, <rcs@xmission.com> wrote:

[another SBG contribution trapped by the mystery mail filter -- rich] -----------

Date: Wed, 21 Apr 2010 15:46:57 -0700 Subject: Re: [math-fun] Trying to recall funny shape From: "Stephen B. Gray" <stevebg@roadrunner.com> To: math-fun@mailman.xmission.com

On 4/21/2010 12:50 PM, Dan Asimov wrote:

I recently read of an odd solid shape, with I think an odd name,

...

that has recently been defined. It may be this:

Take a solid cylinder whose diameter equals its height, cut it in half along a square, rotate one half 90 degrees, and glue the halves back together again.

Does this shape have a name, or is there something similar that does? Apparently it has very interesting rolling behavior.

--Dan

________________________________________________________________________________________ "Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read." --Groucho Marx

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It's called a gefubuwichmuttle. Next question?

-Anonymous

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