Jim: maybe this picture will make Bill's trickery clear. http://graphics8.nytimes.com/packages/other/crossword/GosperLissajous.gif --Michael On Mar 8, 2014 1:08 PM, "James Propp" <jamespropp@gmail.com> wrote:
What are we seeing here? It looks like a rigid object rotating, but what's making it rotate? It looks like the motion is caused by two rollers, either rolling in the same direction or in opposite directions, but either way, how can such a symmetrical set-up impart angular momentum?
I can guess that part of the answer is that the object being rotated is itself asymmetrical, so frictional forced work asymmetrically, but I'm still puzzled.
Presumably if you reversed the directions of both rollers, the object would start rotating the other way.
Are the rollers rolling in the same direction or opposite directions? I've tried peering closely at the video, but I can't tell. Others more mechanical than I can probably work this out with pure reason.
What other effects can be achieved with rollers? (It seems like the sort of transmission system Arthur Ganson would have explored.)
Jim Propp
P.S. I recall seeing a similar effect in the opening scenes of the Superman movie from the 1970s, where the villains from Krypton are penned into an enclosure surrounded by a sine wave.
On Saturday, March 8, 2014, Bill Gosper <billgosper@gmail.com> wrote:
Alan Adler (gosper.org/alan.JPG . "I'm not an inventor, I'm an engineer, dammit," ) is motorizing my Lissajous illusion for G4G11. Lo res (7MB): gosper.org/MVI_0200.mp4 Hi res (314MB): gosper.org/MVI_0200.MOV You can see it on the worktable in the JPG, upended with a pulley removed. Also note the (unrelated) Euler disc. --rwg Poor Leo: To Google translate trompe l'oeil from French to English, spell it the same but say "Tromp Leo". _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com <javascript:;> http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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