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ITSA General Assembly: December 5th - 12th

Author Topic: Maxwell Top  (Read 7357 times)

Jeremy McCreary

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Re: Maxwell Top
« Reply #15 on: March 09, 2016, 04:21:28 PM »

Lourens: Thanks for the book and historical info. I'll be in touch about the former.

Didn't know that all those big names used tops in their research as well, but I'm not surprised. Tops make good demonstration platforms for lots of interesting science.
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Playing with the physical world through LEGO

the Earl of Whirl

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Re: Maxwell Top
« Reply #16 on: May 19, 2019, 10:10:06 PM »

Found the top container and contents called Ptolemy's top.  I took it to Sunday School and fooled around with it a bit.  Looks like what I have is the same in Lourens's collection.  The little piece of rubber that runs along the track is in pretty bad shape.  I am not sure if I need it.  There are also discs of different designs one can use.  They do not fit over that rubber piece.
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Happiness runs in a circular motion!!!

ta0

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Re: Maxwell Top
« Reply #17 on: May 22, 2019, 10:48:38 PM »

Found the top container and contents called Ptolemy's top.  I took it to Sunday School and fooled around with it a bit.  Looks like what I have is the same in Lourens's collection.  The little piece of rubber that runs along the track is in pretty bad shape.  I am not sure if I need it.  There are also discs of different designs one can use.  They do not fit over that rubber piece.

A rubber piece over the axle would add some grip and increase its diameter, what would make it run faster along the track. But it shouldn't be needed to make it work.
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Jeremy McCreary

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Re: Maxwell Top
« Reply #18 on: May 23, 2019, 04:14:56 AM »

A rubber piece over the axle would add some grip and increase its diameter, what would make it run faster along the track. But it shouldn't be needed to make it work.

Experiments with several crude but successful LEGO knock-offs of the Maxwell/Ptolemy top confirm some of the observations noted above...
1. Speed along the track increases with increasing stem diameter, as you said.
2. Speed along the track also increases with increasing stem-track friction, as that reduces slip at high spin rates. Still, metal-metal friction might be enough to get some of the effect.
3. Speed along the track also increases weakly with decreasing CM-tip distance, whether the CM is above or below the tip. So fastest when the CM is at the tip -- in which case, no precession bucking opposing stem motions along the track. (Hence the bell-shaped rotors.)
4. Nothing magic about a spiral track. S-shaped, circular, linear, and polygonal tracks also work well. Fingers, too.
« Last Edit: May 23, 2019, 05:10:08 AM by Jeremy McCreary »
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