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Re: [Phys-L] intermediate axis theorem



I once had a student who went with me to a Feynman appearance at Harvey Mudd College here in Claremont. Feynman's rules on these visits were always that 1) he would only answer questions, 2) only from students, and 3) only if the student convinced him that he or she knew enough to appreciate the answer. My student set up exactly this question and asked, "Is there any intuitive way to understand the result?" Feynman went into deep thought for about 10 or 15 seconds and answered, "no."

My student was elated.

John Mallinckrodt
Cal Poly Pomona

On Dec 26, 2012, at 6:26 AM, Carl Mungan wrote:

I'm looking for an intuitive argument for the intermediate-axis
theorem (IAT), rather than a formal derivation via Euler's equations.

Recall that the IAT says that if you throw a book (taped closed) or
tennis racquet into the air with spin, it will start tumbling about
its intermediate principal axis, in contrast to the stable rotation
observed about its large and small axes.

I don't expect an actual proof, but just a plausibility argument at
the introductory level.Something to the effect of "It makes sense
that rotation is not very stable about the intermediate axis because
..." or "It makes sense that rotation is quite stable about the large
and small moments of inertia because ...."

Anyone have some ideas? -Carl

--
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/
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