Curious behavior of top with coaxial ring

Started by ta0, January 08, 2024, 11:53:56 PM

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Iacopo

#90
I added some tape to the ring to increase its air drag and make it go up and down faster, then I made a slow motion video.

I used a base free to oscillate; spinning on it, the top moved in counterphase relatively to the ring.
The speed of the hula hoop changed from about 370 RPM before to fall on the flywheel, to 440 RPM during the rise.

The phase difference was always more than 180°, for all the duration of the video, with the ring following the spin spindle at about 192° during the fall and about 187° during the rise.

https://youtu.be/uIkfteJxNv4

ta0

Hey, when I thought you wouldn't get more interesting experimental results, you do this beautiful experiment.

You confirmed the change of speed on the ring between rising and falling, but the counter-phase was a surprise.

On the side view I can see that there is about 180 degree phase difference, but I cannot tell the direction in which the stem is wobbling. Is it now opposite to the ring?

Iacopo

#92
Quote from: ta0 on January 25, 2024, 05:53:16 PM
On the side view I can see that there is about 180 degree phase difference, but I cannot tell the direction in which the stem is wobbling. Is it now opposite to the ring?

The stem is wobbling clockwise, like the direction of the spin which is clockwise too.
I never saw the wobble and the spin to be in opposite directions.

Your top too moves in counter-phase. But I was unable to detect the phase differences in your top because there is one wobble in synch with the hula hoop, then another one in synch with the spin speed, and then some precession, making the observation difficult, even if frame by frame, as I did.   

Iacopo

#93
I add some data about the phase differences.
Each dot in the graphs below represents a measure of the phase difference between the top and the ring, as the time, (in frames), of the delay the ring had for to reach the position 180°, (first graph), and 0°, (second graph).
When the dots are below the line 0, it means that the ring was ahead instead of in delay.
But more often the ring is in delay.

The first graph is related to the last video I posted, (reply #90).
The second graph is related to the video below; it was the video that, at first, made me believe that there is a consistent phase difference in one direction; but the second part of the video is more contradictory.

The videos last 37 seconds each but they are in slow motion 1/10 x, so their real time is 3.7 seconds each.







https://youtu.be/5aO0zJ-GVjU

Iacopo

#94
Two more graphs, with measurements from other two videos.
The top was always the same.  In the first graph, there were larger pieces of adhesive tape added to the ring for an higher air drag.  In the second graph the ring had not the pieces of adhesive tape, for a lower air drag.
My idea was that maybe the phase difference was due to the air drag on the ring, and I expected a larger phase difference with higher air drag on the ring.  But, as you can see, the phase difference seems not very different in the two graphs.
So, I don't imagine what could be the reason of the phase difference.

Also, now I think that I have been too hasty saying that I was too hasty;
in the last three graphs there was always a phase difference and always with the same direction, and too many measurements for to consider it a mere coincidence. I took care about the measurements, considering also the parallax error.
The phase difference seems real; in the tested top, the ring, most of the time, hula hoops with a delay of about 5-10 degrees from the stem, (or 185-190 degrees if the top spins in counter-phase).   




Jeremy McCreary

#95
I thank especially @Iacopo and @ta0 for their work and thought on this fascinating system.

A. Would anyone care to summarize some or all of the reasonably solid empirical observations thus far? Would be very grateful, as I'm having a hard time following.

B. For future reference, what should we call this particular novelty top?

"Hoop top" and "ring top" are ambiguous, as many tops are based on hoop- and ring-shaped rotors. (I think of a "hoop" as a simple doubly circular torus and include washers and tubes as rings.)

And "bouncing hoop top" and "hovering hoop top" each describes only part of the characteristic dynamic.

"Hula top" misleads by suggesting that a wobble inherent to the top drives the hoop's orbital motion around the stem, hula hoop-style. Having played with an adjustable working LEGO model, I think it's more the other way round — with the orbiting hoop driving the wobble.

C. These tops aren't really "coaxial" or "coax" tops in the way I originally offered the terms. True, they carry most of their inertia in components capable of independent rotation through various frictional contacts. But the contacts here do little to keep the components in the required coaxial alignment.

I coined the term to cover an interesting genre of LEGO tops I'd been working on. The coaxial part is a key design element.
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

Iacopo

#96
Quote from: Jeremy McCreary on January 28, 2024, 06:09:07 PM
A. Would anyone care to summarize some or all of the reasonably solid empirical observations thus far? Would be very grateful, as I'm having a hard time following.

The relevant parts could be the replies:

#4, with a description of what it happens in this kind of tops.

#56, a formula was found which links the hula hoop speed to the spin speeds of the ring and of the top, and to the diameters of the ring and of the spindle at the contact point.

#61, an empirical demonstration of the effect of the air drag on the top.

There is energy transfer from the top to the ring, (and from the ring to the air), because the ring could not hula hoop for so long by itself, and because the top spins for less time with the ring.  The top I showed in my videos can spin 45 minutes without the ring, and not even 10 minuted with it.

It seems reasonable that this energy transfer from the top to the ring happens through a phase difference between the wobble of the top and that of the ring.
It was found that this phase difference exists, about 5-10 degrees in the observed top. 

Jeremy McCreary

#97
I made a successful LEGO version of this top and am about to start work on the video but still have no idea what to call it.

Suggestions? So far, I've only come up with names I don't like. From a recent post...

Quote from: Jeremy McCreary on January 28, 2024, 06:09:07 PM
"Hoop top" and "ring top" are ambiguous, as many tops are based on hoop- and ring-shaped rotors....

And "bouncing hoop top" and "hovering hoop top" each describes only part of the characteristic dynamic.

"Hula top" misleads by suggesting that a wobble inherent to the top drives the hoop's orbital motion around the stem, hula hoop-style. Having played with an adjustable working LEGO model, I think it's more the other way round — with the orbiting hoop driving the wobble.

Teaser: If you think the action's pretty wild with 1 loose ring on the top, wait till you see what happens with 2!

Wait — how about "loose ring top"?
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

ortwin

Quote from: Jeremy McCreary on February 06, 2024, 11:11:16 AM
..

Wait — how about "loose ring top"?


Looking forward to your video!!


How about: "Da DaRing Top" (The Dancing Ring)

In the broader world of tops, nothing's everything!  —  Jeremy McCreary

Jeremy McCreary

#99
Quote from: ortwin  date=1707239476
How about: "Da DaRing Top" (The Dancing Ring)

Thanks for the suggestion, but I'm going to pass on that one. I think of all tops as dancers with their own characteristic choreographies during undisturbed spin-down.

To push the analogy, I tend to look at a top's resting appearance as its costume. And as in dance, the best costumes enhance the visuals created as the choreography unfolds.
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

Jeremy McCreary

#100
Came across this video in a search on "spinning top with loose ring". We never see it in final form — and SO wish we could have seen it in action — but at least interesting to see how it's made:

https://www.youtube.com/watch?v=Be4XwA0XSYE

Another example:

https://www.youtube.com/watch?v=6yTPQVNLgP4

This time we see a brief demo, but the ring just sits at the lowest level it can reach.
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

Jeremy McCreary

#101
After much searching and testing, have 4 different rings that work at finger speeds with my LEGO knockoff of ta0's Japanese "loose ring top" (for lack of a better name). Several more work with the top held upright in a high-speed electric starter.

Still trying to make sense of the rings that work at finger speeds.The kinematics turn out to be more complicated than I thought — especially with 2 rings at once. Some rings work well ONLY with 2 rings, and some of those work much better with a slightly different "agitator" ring below it.

Holding off on the video till I have something more intelligent to say about what's going on. Meanwhile, found this animation on Iacopo's Video Experiments channel — a real treasure trove for anyone interested in top science.

https://www.youtube.com/watch?v=XU83KmgB15M

Iacopo made it for a different purpose, but it resembles some of the hovering kinematics we're seeing in loose ring tops with a single ring.
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

Iacopo

Quote from: Jeremy McCreary on February 24, 2024, 01:42:22 PM
The kinematics turn out to be more complicated than I thought — especially with 2 rings at once. Some rings work well ONLY with 2 rings, and some of those work much better with a slightly different "agitator" ring below it.

This is interesting, I hope you will make a video about them.  If there is more than one ring, the rings could try to move similarly to the balls in the self balancing tops.  Does the second ring move in counter-phase relatively to the first one ?

Jeremy McCreary

Quote from: Iacopo on February 25, 2024, 01:30:24 AM
Quote from: Jeremy McCreary on February 24, 2024, 01:42:22 PM
The kinematics turn out to be more complicated than I thought — especially with 2 rings at once. Some rings work well ONLY with 2 rings, and some of those work much better with a slightly different "agitator" ring below it.
Does the second ring move in counter-phase relatively to the first one ?

Short answer: Yes, during a common terminal state I call the "quiet hover" (QH).

In this state, both rings are hovering 180° apart, and the top and rings are rotating in unison — as if all part of the same rigid body. The top goes quiet — none of the clattering of rings or scrubbing of the tip heard pre-QH.

If up-and-down ring motion occurs, it's pre-QH.
Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

Iacopo

Quote from: Jeremy McCreary on February 25, 2024, 04:04:25 AM
In this state, both rings are hovering 180° apart, and the top and rings are rotating in unison — as if all part of the same rigid body. The top goes quiet — none of the clattering of rings or scrubbing of the tip heard pre-QH.

If up-and-down ring motion occurs, it's pre-QH.

Thank you, Jeremy. 
Also I would like to know, if possible, if the AMI is littler or larger than the TMItip, in that top. I would expect two different behaviours, in the two cases.