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Are fidget spinners tops?

Yes
No

Voting closes: July 03, 2020, 09:11:18 PM


Author Topic: Are fidget spinners tops?  (Read 183 times)

Texture

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Are fidget spinners tops?
« on: March 25, 2020, 09:11:18 PM »

There are many kinds of fidget spinners, but the word "top" was never related.
Is a fidget spinner a top? It has a spinning function, and displays the gyroscopic effect, and gyros are tops right? Vote your opinion here.
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ta0

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Re: Are fidget spinners tops?
« Reply #1 on: March 25, 2020, 09:44:48 PM »

I think your poll is going to be very one sided . . .  >:D
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the Earl of Whirl

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Re: Are fidget spinners tops?
« Reply #2 on: March 25, 2020, 09:56:56 PM »

When I put a stem in my fidget spinner it is definitely a top!!!
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Happiness runs in a circular motion!!!

Jeremy McCreary

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Re: Are fidget spinners tops?
« Reply #3 on: March 25, 2020, 11:21:59 PM »

A strictly operational definition that some of us go by...

Support an object, natural or manmade, on a narrow contact below its center of mass. If the object
(1) falls over right away when you let go at rest, but
(2) stands against gravity for at least a few seconds when you spin it fast enough about the axis through the center of mass and the contact,
then it's a true top, no matter how the object looks or how or why it came to be.

Fidget spinners generally fail on (1) as sold. A classic toy gyro with a caged rotor qualifies as a top, as it meets both (1) and (2), but a gimbaled gyro with the rotor shaft supported against gravity at both ends fails on (1) by design. Pump "tops" and other traditional top-like spintoys with feet to keep them from falling over at rest represent a gray area, as some could probably meet (1) and (2) with the feet removed.
« Last Edit: March 26, 2020, 06:14:18 PM by Jeremy McCreary »
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Playing with the physical world through LEGO

Mermouy

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Re: Are fidget spinners tops?
« Reply #4 on: March 26, 2020, 05:07:34 PM »

A strictly operational definition that some of us go by...

Support an object, natural or manmade, on a narrow contact below its center of mass. If the object
(1) falls over right away when you let go at rest, but
(2) stands against gravity for at least a few seconds when you spin it fast enough about the axis through the center of mass and the contact,
then it's a true top, no matter how the object looks or how or why it came to be.

Fidget spinners generally fail on (1) as sold. A classic toy gyro with a caged rotor qualifies as a top, as it meets both (1) and (2), but a gimbaled gyro with the rotor shaft supported against gravity at both ends fails on (1) by design. Pump "tops" and other traditional top-like spintoys with feet to keep them from falling over at rest represent a gray area to some.
Wahou, that's a pretty clear definition, thumb up Jeremy!
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Texture

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Re: Are fidget spinners tops?
« Reply #5 on: March 27, 2020, 08:29:18 PM »

A strictly operational definition that some of us go by...

Support an object, natural or manmade, on a narrow contact below its center of mass. If the object
(1) falls over right away when you let go at rest, but
(2) stands against gravity for at least a few seconds when you spin it fast enough about the axis through the center of mass and the contact,
then it's a true top, no matter how the object looks or how or why it came to be.

Fidget spinners generally fail on (1) as sold. A classic toy gyro with a caged rotor qualifies as a top, as it meets both (1) and (2), but a gimbaled gyro with the rotor shaft supported against gravity at both ends fails on (1) by design. Pump "tops" and other traditional top-like spintoys with feet to keep them from falling over at rest represent a gray area, as some could probably meet (1) and (2) with the feet removed.
Great definition!
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Jeremy McCreary

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Re: Are fidget spinners tops?
« Reply #6 on: March 28, 2020, 02:26:27 PM »

Of course, a properly designed fidget spinner can also be a true top...

https://youtu.be/9rl5JhY7Y-Y

This one doesn't stay up very long, as LEGO plastic is only 5% denser than water, air resistance is considerable, and the bearing's nowhere near as good as a typical fidget bearing. But the freely rotating rotor can still acquire enough angular momentum to hold up the entire top for at least a few seconds.

I call tops with independently rotating coaxial components "coax tops" for short. Lots of exciting design opporunities in this genre -- especially WRT visual effects.

Another example at 2:00 and 5:25...

https://youtu.be/YsyD4iTeWFM

« Last Edit: March 28, 2020, 03:33:15 PM by Jeremy McCreary »
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Jeremy McCreary

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Re: Are fidget spinners tops?
« Reply #7 on: March 29, 2020, 02:18:39 PM »

The top-like "spindulums" below fail on criterion (1) above because they don't fall over at rest -- not because their tips or the bottle cap do anything to keep them upright, but rather because their centers of mass (CMs) are below their recessed contacts by design.

https://youtu.be/u7_azTiWxyw

The precise location of a spintoy's CM along its spin axis is often unclear in practice. But 2 simple behavioral tests provide valuable info on CM location relative to the contact:

A spintoy with a tip and supporting surface that do nothing to keep it upright or push it over at rest has a CM below the contact if you see it...
A. rise to the vertical on its own and return to the vertical after small perturbations in tilt, pendulum-style, as at 0:32, or
B. precess in a retrograde direction (opposite the spin), as at 3:50.

In practice, Test A -- to be performed without spin -- tends to work better when the spintoy's mass or CM-contact distance along the spin axis is relatively large. Make sure that the tip and supporting surface don't interact to muddy the water.

Test B -- to be performed with spin -- turns out to be more reliable when the CM-contact distance approaches zero. Usefully, precession rate is proportional to this key distance but independent of total mass. And all precession ceases when it's exactly zero, regardless of mass or spin rate.
« Last Edit: March 29, 2020, 05:06:39 PM by Jeremy McCreary »
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Texture

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Re: Are fidget spinners tops?
« Reply #8 on: March 30, 2020, 08:54:36 PM »

Of course, a properly designed fidget spinner can also be a true top...

https://youtu.be/9rl5JhY7Y-Y

This one doesn't stay up very long, as LEGO plastic is only 5% denser than water, air resistance is considerable, and the bearing's nowhere near as good as a typical fidget bearing. But the freely rotating rotor can still acquire enough angular momentum to hold up the entire top for at least a few seconds.

I call tops with independently rotating coaxial components "coax tops" for short. Lots of exciting design opporunities in this genre -- especially WRT visual effects.
Right!

Another example at 2:00 and 5:25...

https://youtu.be/YsyD4iTeWFM
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