Rigid Body Motion and the Dzhanibekov Effect

[@StellaLotus]

Brilliant and certainly facinating!! I enjoy this video and the excellent explanation, description and awesome visual example of the Dzhanibekov effect.

[@AK56fire]

Incredible... I appreciate the effort you've put into making such a detailed video... Keep'em coming.. It's great work..

[@PhysicsUnsimplified]

Thank you Amit...

[@MrLikeAsatellite]

This is so far the best explanation for the effect I have found, still challenging the viewer with some brainwork though. What bothers me the most with other videos is the permanent use of weirdly shaped nuts, bolts, tennis rackets or other objects which completely obstructs the inner workings.

[@ryan_6984]

Very very good. When I did my Degree in Physics I gained knowledge of rotational motion but not an understanding. I was very interested in the Earth's magnetic polar shifts that happen and I think this is a fundamental part of the explanation for that.

[@davruck1]

I just got back into classical physics. So much cool stuff that I think gets overlooked by everyone wanting to publish jaw dropping theoretical physics papers and talk all about relatively meaningless things like spacetime getting ripped. I’m also an engineer so I prefer stuff I can actually measure and see. I’m in civil engineering so calculating moments of inertia was part of our life.

[@kevinj5989]

The ancient literature of Earth contains MANY references to "the earth turned over", "north became south, and south became norht", "the sun rising in the west and setting in the East", and so on. One says, something like, "the sun reversed direction, rising in the west, etc, sometimes OBLIQUE," and so on. And there is a HUGE amount of evidence of giant floods in the geologic record, with a noticeable north-south bias (from gouges and rock trails and flood paths in the land). Could they be talking about the Dzhanibekov effect applied to Earth? Earth has a cataclysm every 12,000 years or so. Could you please say a few words on how the DBE might apply to the Earth? Thank you.

[@vitalxs2947]

I am no physicist, or scientist, but it appears to me that this all have to with 2 things: Symmetry and Asymmetry. Assymetry makes objects uneven in terms of its weight, in relation to the center of the object. This weight and shape difference will make object to be off balance, relative to its center, even if balance can be found at some other point of the object. Therefore, asymmetric objects, when rotated, will always shift balance to the center of the object, and by doing it will create the unbalance, which rotating object then would attempt to compensate for (the missing symmetry), by temporary flipping the asymmetric part to the side that is missing it, then the balance is briefly restored before it again gets out of balance compare to its center, but now on the other side, and then it flips back, thus creating a cycle, that is controlled by the speed of object rotation, and that depend on the distance between the center of the symmetric portion of the object, and assymetric portion. The assymetric part of the object is the portion that begins where symmetric portion ends. So, I think if the object is symmetrical, and is rotating along its center, no flipping would occur.

[@original1up]

The analogy with the pendulum made it really clear

[@mufaddalkapasi1778]

What a wonderful explanation! I was unable to sleep for soo many days due to this doubt , thank you very much for clearing that. Keep up the good work👍 Awesome video👌

[@PhysicsUnsimplified]

Thanks Mufaddal!

[@pluspiping]

Makes perfect sense AND is beautiful to watch. I'll be coming back to watch this just for fun. Thanks!

[@JohnGilmour]

The best explaination I have see to date. Thanks. I am almost there.

[@mike-synthetica]

A fantastic explanation that makes things crystal clear. Thank you!

[@georgefan2977]

That is exactly what I thought. A small disturbance (where the spinning axis is not completely perpendicular to our frame of reference, resulting in a irregular distribution of mass) causes this periodic motion of instability. The other videos did not mention this at all. Thank you so much!

[@user-dn5bx2iu3e]

Brilliantly explained classical perspective. I'm inspired to try recreating the simulation to tweak its initial momentum, really elegant stuff. Thank you.

[@TimAskerov]

This is a very intutitive explanation/illustration of the complex physics in action. Thanks!

[@undecidedmajor1664]

Very intuitive. Excellent explanation

[@comeraczy2483]

Thank you very much! I was very disappointed by the glaring gaps in Tao's/Veritasium "intuitive explanation". You brilliantly addressed these gaps and the visualisation offered by your simulations is excellent.

[@Odisovic]

And since the earth also does not have "uniform mass", the question is why in the video it rotates and the earth does not do this? Or is the pole swap actually the earth turning and the Mayan legend of us already being a third earth is linked to a catastrophe where when the earth turns (ala the matrix in space) then the mass of the oceans overflows and there is a great flood?

[@meeklion]

Great video!

[@melmcintyre3211]

Excellent work

[@jaimeeoww]

this helps me understand a lot! thank you for explaining!

[@fcvgarcia]

Thanks for the excellent explanation!!!!

[@5eurosenelsuelo]

That's a nice video! Thanks and congratulations.

[@Phelan666]

What are the implications for centrifugal "gravity" in space vehicles? Does this make it impossible, or is it possible to design around this effect?

[@corbinaquino]

My physics background is quite elementary but I stumbled upon these concepts and I am really fascinated by them. I am interested in calculating how the angular velocity axis/vector moves as a function of time (relative to the object and also relative to the inertial frame). How would I go about learning the necessary concepts in order to calculate that? Thanks!

[@birefringent2851]

Everything you need is in Landau & Lifshitz Volume I (Classical Mechanics)

[@NicleT]

Absolutely beautiful and well demonstrated. However, I was curious to see the simulation with the “T” shape mass as in the space experiments of this effect, instead of two symmetrical sets of masses.

[@StevenDenenberg]

I have followed the equations and see why rotation around the intermediate access is “unstable “. But what I can’t find in the equations is why, as the body tumbles and flips and the red axis inverts, why does it apparently come to rest again until the small perturbations and the instability from Euler’s equations cause it to flip again. I don’t see where the equations indicates that there is a period of flipping and a pause in between flips. Any insight would be appreciated!

[@abhishah7139]

You have provided the best explanation of the effect, far better than what Derek did. I would have liked it even more if you had spent more time on the simulation, different angles of rotation. I also still don't understand why when the red axis was at 80 degree at slow speed, the plane was not rotating at all. I would like to see a timelapse of it and if it's rotating along the y axis at all or not. You said it doesn't but I still don't understand why. If you could provide a site on which a noob can play around (without using math), I think it would be great. I have many more questions but I wouldn't bother you with that much! I really appreciate your efforts kind sir, and would be recommending to be pinned in the original video.

[@PhysicsUnsimplified]

Thanks Abhi, If I recall correctly, you can't see the precession ( the rotation of the plane) in some of the video clips simply because the precession is too slow. That's why I made the one video clip with everything sped up, so you can see the precession of the plane quite clearly.

[@evanrinehart]

At 5:08 it appears as if the angular velocity (gold) begins aligned with angular momentum (blue) while not aligned with any principal axis. That seems inconsistent with L = Iω when there are three different principal moments of inertia. In the body fixed frame you could imagine L scaling non-uniformly along three axes wrt ω

[@markcoleman9892]

I watched your explanation immediately after the Veritasium video, courtesy of KZbin's recommendations list. Both together is a good way to go! In the case of possible application to Earth's surface "rolling over" (there are too many ancient stories to ignore), one wonders what effects occur if an unpaired mass (A) is added to a spherical surface defined from the 4 initial masses (additional forces are transmitted via the "surface, which may be too complex for a "simple" demonstration)? How does that affect the rotational pattern? Then add another mass (B) such that the axis between A and B does NOT pass directly through the center of the spherical shape. I can visualize the setup, but my education is insufficient for predicting the behavior. [Gyroscope behavior in microgravity, as presented in NASA videos, is quite stable, but there is increasing evidence that Earth's interior layers are not as homogeneous as portrayed in the typical geology books, which makes the Dzhanibekov Effect far more possible.]

[@TeranceHealy]

Well explained. If you take the cyan to be the equator and the red to be the north and south poles, , based on mass one axis heavier than the other, applying this rule to the earth, can you predict the period of time where the flip would occur. Does this e plain the Younger Dryas and the cataclysm described in the book ADAM & EVE? It would also seem to suggest that there could have been previous civilizations on the earth which have been completely wiped away. Exceptions being the pyramids and the Richat structure where seems remarkably precise measurements for the foundation of the city of Atlantis. Would we feel the earth wobble as the poles moved while the impending flip approached?

[@kevinoboyle8939]

Could this be exploited to create day night cycles on a space station? Is there a variation of the centrifugal force on the major axis?

[@blinded6502]

Have you taken a look at PGA (projective geometric algebra)? Rigidbody mechanics described in it's terms are quite elegant.

[@brianmackey3949]

Zero gravity. Great. What about atmosphere and electromagnetic inputs? Would it be bumped less at absolute zero, in no air, in the dark, without magnetic waves?

[@jaekyunglee5646]

Thank you so much.

[@mattrodgers7354]

So would it still do it if all 3 axis the same mass? Would it do it if it had 4 ends of equal weight?

[@omargaber3122]

Great and wonderful

[@SeanSpecker]

right .if you were to view a point two dimensionally along its trajectory like an occilating wave...what does the flip look like?

[@oddinvestigator]

very good video

[@MrSyedbasit]

Why they ‘red masses’ switch positions at fixed intervals of time not continuously

[@barada6820]

You didn't fully explain what happens in the case of rotation around the smallest moment of inertia.

[@SeanSpecker]

that top teardrop of rotation is just like our precession on earth. bizaar. what do you make of that? that the earth DOES have 3 axis of rotation? so is this effect the reason behind our current precession of the equinox leading to the completion of the rotation before the flip. nonsense ideas i know but if i can think it then its possible. what do you think of this?

[@vladpavlov7341]

хорошее видео- показывает как объект неправильной формы пытается найти равновесие и выбирает алгоритм поиска, но как только исчезает точка крепления, нивелирующая всё многообразие центров тяжести, возникает ХАОС, назовём его -Простейший хаос, потому что природа, в отличие от человека, всегда ищет простейший путь. и находит его, а человек , видя это, решает, что систематизировал ,, кувыркание,, предмета неправильной формы. Золотое сечение всем в помощь😎

[@surrealchronos4501]

Why isn't this used to explain atomics theory, as the energy and electrons are more or less correctly alligned... I found if we change some views this is the level of small this might function on. The way I see it is as Molecules become larger the oscillation frequency gets larger.... It's not as though they are spinning physically but the atoms at that level always are? In a state of energy due to gravity! So what then and does anyone else think as I do? Interested to hear others opinion

[@joshuatreeskincare6492]

So, how does this apply to planet earth? Does our fossil fuel consumption warm and melt ice caps, redistributing mass? We see that the magnetic poles move throughout history, and there is talk of a great flood in every religion. The water would move independently…. And has significant momentum! What about how moving weight from the poles away from the primary axis will slow the rotation in that plane… and potentially increase the speed of the oscillations in the axis loosing weight (increasing potential for a rapid “flip”). This would defiantly be longer hotter days, and colder nights… more turbulence. Could that influence our magnetic flux of the planet? Could a change in flux affect the fluidity of the magma (a ferro fluid) that our continents are floating on?

[@TheSatiah]

That's so very cool 😎

[@rodolforamirezagredano5433]

Estos son estudios técnicos muy interesantes para toda la jente muy buena programasion

[@ztac_dex]

My GR prof used this perturbative approach and negating the higher ordered terms since it's the easiest to visualize and explain

[@picroger4510]

Amazing.

[@onderozenc4470]

In my opinion, this phenomenon is no different than the "helicopter effect". In helicopters, when the main propeller rotates it processes around the rotational axis at the same time which creates a torque T=dL/dt = L x W where "L" corresponds to the angular momentum of the propeller, "W" represents the precession angular velocity which is almost the same as the angular velocity of the propeller. This torque is in the nose to tail direction on the helicopter and this is why they install a tail propeller which has to spin faster than the main one because of its smaller inertial moment to create an equal opposite torque induced by the precession of the main propeller. This is owing to this reverse torque created by the tail propeller , helicopters don't flip around.

[@jaydenwilson9522]

Do you happen to have an INTUITIVE explanation for the Intermediate Axis Theorem? Feynman said "No." And my teacher and Einstein always said that if they can't explain it in common sense terms to the laypersons then chances are that they don't know what they are talking about.

[@adambzdak]

One can levitate objects using the air stream and nicely observe the Dzhanibekov effect. See kzbin.info/www/bejne/g6DFfqaCq6ycgtU and this one kzbin.info/www/bejne/nJ7MmHt-lp6Hlac for a more detailed discussion.

[@michaelteran3844]

the reason for these experiments in space were to determine how our Earth is spinning object with lopsided weight will flip the Earth over like it has done many times in Earth's history! We are in for a hell of a ride once again. Oh yeah I forgot to mention that the sun will micronova triggering the flip.

[@SeanSpecker]

so...can you demonstrate that the earth doesn't do this too?

[@hassanabdullah6742]

The earth is somewhat a sphere and it does not have that instability of moment.

[@ltzhk]

Earth is an asymmetric ellipsoid, not a perfect sphere, correct?

[@Farooqueakhan]

Probably this is the effect, which causes the flipping of magnetic poles with respect to the geographical poles periodically. I hope the next video that the author of this video is going to share will go into the calculation of this period.

[@ltzhk]

@@Farooqueakhan it should be interesting to have a more detailed model. Earth's body of water, as well as the entire sphere, is not rigid, and under stress that might even contribute to the effect.

[@ethandennis368]

Yes, the earth is an oblate spheroid spinning in its minimum energy state (maximum principal moment of inertia). This is a given even without our observations which show this, because things like the sloshing of water will dissipate enough energy over time to ensure that the earth goes towards its lowest energy spin state.

[@thelukeewan7602]

The beautiful minds commenting here light my fire

[@johnnemo4146]

I'm not a physicist or mathematician, nor having to do with anything mechanical, but what I find immediately problematic is the "instable equilibrium position", which should be analogous to the one of the pendulum, when it is not obvious at all, because what stabilizes it in the Dzhanibekov effect is the rotation. The same rotation which takes it out of equilibrium at 8:14. So why does it stabilise it? Perhaps because the axis of the small masses is linked to the rotation of the big masses, creating a gyroscopic stabilization (that point should be further analyzed). But why does it go out of stabilization then. It seems to me that the phenomenon is caused by small mass asymmetries of the big masses, or generally, along the axis of the big masses, which make the real rotation axis not perfectly centered in the physical axis of the object. The two axes are misaligned! In the case of a T-shaped object like in this video: kzbin.info/www/bejne/Z4ezl42Vjd-cqbc at 5:16, that would mean a small asymmetry in the masses projected from the rotation axis, causes the physical axis of the object to be misaligned with the real axis of rotation. This misalignment of the real axis of rotation and the real physical axis of the object, would be the cause of the phenomenon, in my (very quickly brushed) view.

[@johnnemo4146]

The flip should happen and stabilize gyroscopically until the basic misalignment position, and then resume out of it... Hmmm...

[@bgold2007]

So called yellow color impossible to see

[@mikedl1105]

Physics Girl and Rodney Mullen taught me this first

[@slowquik]

Will it ever happen to Earth?

[@SeanSpecker]

hope you get my simple minded reasoning.

[@harthouser5177]

And a moon is orbiting this.

[@robertfowler348]

So why does a phenomenon known and undeerstood for at least 150 years and appearing in text books for at lesat 115 years, e.g., Whittaker's Analytical Dynamics (1904) get renamed for a Russian cosmonaut? Is it because everything that happened before the Internet can safely be claimed to be invented anew?

[@A.Dajlida]

The 'tennis racket' bullshit explains nothing, and was obviously created to lead astray from the real Djanibekov effect. What real Djanibekov effect shows is that the spin (as seen by observer) is kept the same. That is, the spin of the nut ITSELF is changed to opposite with each flip. This effect evidently shows that in rotation, spin is kept not by material body but by ether.

[@frankcorr6566]

I tried running this in Glowscript and it stopped unexpectedly. There are very few facilities in Glowscript for debugging so I installed Microsoft Visual code as described here . kzbin.info/www/bejne/n3bbi6avdr5-bNE . It was stopping because it was not recognizing the 'else if' at line 90. The program is read only so I took a copy and ran it in my own space. Simply changing 'else if' to elif on line 90 makes it work. This is a tremendous piece of work.

[@JohnGilmour]

I think the Earth is in trouble but nothing new.