The Bizarre Behavior of Rotating Bodies

Spinning objects have strange instabilities known as The Dzhanibekov Effect or Tennis Racket Theorem - this video offers an intuitive explanation.
Part of this video was sponsored by LastPass, click here to find out more: ve42.co/LP
References:
Prof. Terry Tao's Math Overflow Explanation: ve42.co/Tao
The Twisting Tennis Racket
Ashbaugh, M.S., Chicone, C.C. & Cushman, R.H. J Dyn Diff Equat (1991) 3: 67. doi.org/10.100...
Janibekov’s effect and the laws of mechanics
Petrov, A.G. & Volodin, S.E. Dokl. Phys. (2013) 58: 349. doi.org/10.113...
Tumbling Asteroids
Prave et al. doi.org/10.101...
The Exact Computation of the Free Rigid Body Motion and Its Use in Splitting Methods
SIAM J. Sci. Comput., 30(4), 2084-2112
E. Celledoni, F. Fassò, N. Säfström, and A. Zanna
doi.org/10.113...
Animations by Ivy Tello and Isaac Frame
Special thanks to people who discussed this video with me:
Astronaut Don Pettit
Henry Reich of MinutePhysics
Grant Sanderson of 3blue1brown
Vert Dider (Russian KZbin channel)
Below is a further discussion by Henry Reich that I think helps summarize why axes 1 and 3 are generally stable while axis 2 is not:
In general, you might imagine that because the object can rotate in a bunch of different directions, the components of energy and momentum could be free to change while keeping the total momentum constant.
However, in the case of axis 1, the kinetic energy is the highest possible for a given angular momentum, and in the case of axis 3, the kinetic energy is the lowest possible for a given angular momentum (which can be easily shown from conservation of energy and momentum equations, and is also fairly intuitive from the fact that kinetic energy is proportional to velocity squared, while momentum is proportional to velocity - so in the case of axis 1, the smaller masses will have to be spinning faster for a given momentum, and will thus have more energy, and vice versa for axis 3 where all the masses are spinning: the energy will be lowest). In fact, this is a strict inequality - if the energy is highest possible, there are no other possible combinations of momenta other than L2=L3=0, and vice versa for if the energy is the lowest possible.
Because of this, in the case of axis 1 the energy is so high that there simply aren't any other possible combinations of angular momentum components L1, L2 and L3 - the object would have to lose energy in order to spin differently. And in the case of axis 3, the energy is so low that there likewise is no way for the object to be rotating other than purely around axis 3 - it would have to gain energy. However, there's no such constraint for axis 2, since the energy is somewhere in between the min and max possible. This, together with the centrifugal effects, means that the components of momentum DO change.

[@joedaly6887]

As a carpenter for over fifty years I've recognized this behavior with flipping of a hammer because I early on decided to teach myself to juggle hammers. I tried to prevent the twist-flip with absolutely no success. It became clear there was more stability in working with the flip instead of against it. This explanation is such a relief! I thought it was a personal curse. Now I realize hammers are the perfect object to demonstrate this motion because they, unlike tennis rackets, have no symmetry about any axis!

[@johnpossum556]

You just got defective hammers.🤣

[@joedaly6887]

@@johnpossum556 additional evidence: rip claw configuration in hammers produce more consistent axial twisting.

[@pmcgee003]

Once again ball pein better than claw hammer. 😀 😉

[@alsteiner7602]

@@joedaly6887 that has been my experience flipping a straight claw for years--it never rotated about the intermediate axis. Very east to flip

[@jamespppyacek342]

Yeah. Same here. Carpenter. Hammer. Flipping.

[@rv6amark]

I was a dynamicist in the aerospace industry for 43 years, and THAT is the BEST plain text explanation of this behavior I have ever seen! Fantastic!

[@gregsmith1719]

Wow! You have sold me! I'll watch it again!

[@xccghvbno1063]

Then you're probably the person to ask what are the odds that the plates shifting around could in fact change the Earth's moment of inertia to where it could possibly effect the crust in a dramatic way? Just curious not every day one has a chance to ask a question to an expert who's possibly even thought about the same But actually with the educational background to get through the weeds of the problem and Come up with a Realistic hypothesis even if it is just A rough mental outline

[@danielhope2924]

Was I watching this correctly to assume that if the frozen poles had enough elevated weight and then melted lowering that weights and even some of the water dissipating towards the equator, this could shift the moment of inertia ?

[@xccghvbno1063]

@@danielhope2924 very good point. Time For me to go research exactly how much ice is estimated to be Frozen.Thanks for the input

[@3.k]

@@danielhope2924 The poles are where the least mass is, on the spinning axis. So if their mass would be distributet all over spinning system, the spin should become even more stable, because the mass around the equator would become even more significant.

[@2false637]

This is the content I subscribed for. Well done!

[@winkil1]

Agreed

[@alexanderkurz3621]

I love how you manage to pack so much into one video, physics, history, personal interest stories, tangents to pursue further ... this is how I would like to teach and I know how hard it is to do

[@llll-lk2mm]

This explaination is beautiful when you're actually learning this stuff in school... keeps me wanting to know more. Thanks Veritasium!!!

[@Tattootin]

Never been a more deserving like to a comment on a video!

[@llll-lk2mm]

@@Tattootin :)

[@mapk4655]

I watch this as a break from stupid school work.

[@jamessmith2622]

@@llll-lk2mm %ï

[@RitaMaru11]

@@mapk4655 Good

[@davidking2846]

I've been flipping tennis rackets for years and never been able to get my head around this effect. Incredible.

[@fxm5715]

I always figured I was just giving it some spin around the long axis unintentionally, because I didn't have enough dexterity to do otherwise. Now I know better.

[@naverilllang]

I always assumed it had to due with imbalanced rotation compounded by air resistance. Which I guess was half right.

[@timbeaton5045]

Was this a Head, tennis racquet by any chance? 😎

[@po_thiago]

I've also been flipping tennis rackets for years, but never been able to get my head away from its path on its way down... ;(

[@larryrich327]

David King I always thought it was my skill that caused the flip I didn't know it was doing it on its own 😕

[@qfmarsh64]

As a kid, I would frequently watch my dad flipping the TV remote control in his hand and studying the inevitable half-turn in its flight pattern. He concluded that his wrist was subtly imparting spin. If he were alive today, his mind would probably be blown watching this video.

[@llll-lk2mm]

aww that's so cool

[@elgoog-the-third]

"He concluded that his wrist was subtly imparting spin." Well, as we've learned in your video, your dad was right

[@roasty247]

Cannot tell you how many hours I have done this with a TV remote too, trying to get a straight flip. Futile all along.

[@siggyretburns7523]

This physics trick puzzled me years ago when I was flipping a claw hammer. No matter what I did or how I flipped it it would not just flip with the claw on the right and the hammerhead on the left. It would end up that way but half way through the flip, the claw and hammer would switch sides. From what I understood of physics at the time, I assumed it was because either the claw or the hammer weighed more than the other and gravity interrupted the momentum. But this video proves me wrong. One thing I dont understand is that if its perfectly balanced, it shouldn't happen. I still think that Earths rotation has something to do with it.

[@elgoog-the-third]

@@siggyretburns7523 Yes that is correct, if it were perfectly balanced, it would not happen. But there is no such thing as "perfect" in practice.

[@tonyfourpaws4511]

I got in trouble at work today because I was tossing various objects and watching the flip. I tried to explain it to the boss but he wasn't having it. He fired me. Now I have more time to watch your videos!

[@HyperVectra]

You must not have explained it well. Sometimes people need to experience it themselves to truly understand the concept. If you cut his brake lines, his car should spin around the maximum angle of inertia.

[@HyperVectra]

@@nramrez Oh.. could you tell me then please?

[@thedevilinthecircuit1414]

Time to convert some of that inertia to getting a job 🙂

[@SvenSamray]

Happens when you tossing dead bodies around like a mad man.

[@duckblug609]

@@HyperVectra

[@EtzEchad]

"The goal of this video is to prove Feynman wrong." You have high ambitions, young man!

[@CapaNoisyCapa]

As soon as I heard him say that I came to see this comment. Was not disappointed. High ambitions, indeed.

[@raykent3211]

Very brave! Feynmann: so you're saying that loss of kinetic energy causes a change in rotational axis to that of maximum moment of inertia, when usually it just slows things down? Since when was inertia intuitive? My ref to surely you're joking.... great video, though.

[@rubiks6]

I think he was quite successful. Raspberries to Feynman.

[@DobromirManchev]

@@raykent3211 Indeed, it all depends on what you call "intuitive". I think inertia is a step higher than what most people will find intuitive.

[@rogerwhittle2078]

My first reaction was that it is quite rude to make such an attempt, if not actually heretical - Feynman being such a towering icon of scientific thinking. Then I thought 'Nah, Feynman would love it.' I was fairly comfortable with understanding this phenomenon, but I suddenly had a very nasty moment when the subject of the Earth doing the same was raised. It being a fluid filled object and everything - magnetic poles flipping as evidence. I'm glad he could assure us it would not. So, did he prove Feynman wrong? Because my brain still hurts.

[@kodycook1505]

I'm a carpenter and I'm constantly flipping my hammer while I'm not busy. I've wondered for the past 10 years (I became a carpenter in 2010) why is it the head and claws of my hammer flip flop when I flip my hammer head over handle. I thank you for this video!! I suffer from ADD/ADHD and I find myself pondering this very often (driving myself nuts over it). Thanks again for the answers!!!!

[@albertoserrano4736]

anxious minds made modern world possible

[@Lugnut64052]

First thing that occurred to me too. Been a carpenter for many years. Hammers will do that every time you flip them.

[@pseudogamer4559]

Yeah.....I understand ur struggle for all this year's I mean u could have done nothing about it..... If someone from MIT got this idea he would have derived it in few days because of their technology and advancements in maths n physics ..... I've gone through the same thing many times .....it takes time to solve problems .....unless i meet some expert on that topic and gain complete idea .....then i can solve it xd

[@carlosbyrd4519]

@Alexandre BrunetI hope so

[@squarerootof2]

@Compliment Thief Stop thieving.

[@alvirahesc7436]

"Babe, come over, im home alone" "No, babe, Im solvin a centuries old math problem."

[@ragnarok7976]

The problem: Where does she want to go for dinner.

[@illogicalparadox]

What a chad, keheheh.

[@davidh1206]

You’re dating the wrong person if this isn’t an acceptable alternative to dinner

[@TheNebulon]

He bumps her on the secondary axis to get her to turn around

[@NickRanger]

@@TheNebulon it's the 3rd axis we all want

[@youtubeboi855]

I have a feeling that when Feynman replied "No" to the question, it was because he considered even this "intuitive" explanation, not that intuitive for most non-physicists/engineers.

[@jaydenwilson9522]

what question?? im curious and havent read much feynman

[@conormurphy341]

@@jaydenwilson95225:51

[@yommish]

@@jaydenwilson9522 it’s in the video

[@jaydenwilson9522]

Its own Axis disrupts its harmonious dance... Which temporarily causes imbalance, but even then... It still seeks to return to a balanced state. And it always will return to that state... No matter how dysfunctional. - Jayden Wilsons "intuitive" explanation of the intermediate axis theorem.... guess I'm smarter? @@yommish

[@yommish]

@@jaydenwilson9522 wow, I guess you are smarter than Feynman

[@andrewchapman2039]

Video: contains the phrase "prove Feynman wrong" Also video: doesn't use this phrase as clickbait. I salute you.

[@shadowcoder19]

One could still argue that it is clickbait. Because an intuitive explanation is relative to the person receiving the explanation. And Feynman probably knew his students wouldn't be able to understand this explanation. Hence it being hard for him to intuitively explain it to his students.

[@funkyflames7430]

Living Legend I concur. Derek in this case used 3d animation to explain this phenomenon while Feynman would’ve been limited to making some drawings and mental pictures. The explanation subjectively intuitive but intuitive nonetheless, at least more so than math equations.

[@TheLaXandro]

He could make a "3d model" out of a plate and a pencil to mark the axis out, and demonstrate it in a largely similar way.

[@vsiegel]

"prove Feynman wrong" is not working clickbait - it's so obviously spam that nobody would click it. And then... he actually did what?

[@mvmlego1212]

Of course, it's not "bait" if he actually does it (which, in my opinion, he did). I still appreciate that he gave it an informative and non-confrontational title, though.

[@shawn576]

I always assumed this happened because I was adding spin without realizing it. The theory of a rotating object trying to minimize its kinetic energy actually makes a lot of sense.

[@lukeernst2101]

I mean, you are adding spin without realizing it. In the point mass simulation even the intermediate axis is stable until there was a tiny deviation from exactly straight spinning. Whether it’s you unknowingly rotating it along an axis slightly different than the true intermediate axis, or air later misaligning it, it’s almost impossible to not see this effect in practice

[@ayooshiyer8621]

@@lukeernst2101 if air is causing this misalignment why do we still see this effect in space ?

[@singh2702]

@@ayooshiyer8621 If the intermediate axis is pulled into a spin by the larger axis then this intermediate spin can only end once the larger axis has spun itself 180 degrees. By this deduction alone the outer intermediate masses must be switched hence the flip.

[@hellencitaUwU]

@@ayooshiyer8621 cause there is air on that cabin, remember that they are still breathing... i think if they left it in space without air we cant see this phenomenon.

[@rarebeeph1783]

@@hellencitaUwU the air has nothing to do with it. as derek (veritasium) said, in the reference frame of the initial rotation of the disk, the centrifugal force inherent to the rotation is what causes the disk to flip, with a frequency dependent on how much deviation the smaller masses are initially given from the axis of rotation. that's why the wingnut spins for so long between each flip, while most other things flip much sooner: the wingnut was given very nearly axis aligned rotation when it was spun off of its screw, so the centrifugal turning forces are very small for a rather long time.

[@Koutentogiwrghs]

A colleague pointed me to this great video! I was fascinated to find that it also contained two additional facts about the great condensed matter physicists of the past century. 1) If you claim that any physical concept is not in the Landau-Lifshitz books, most probably you have not looked for it as carefully as you should. 2) It is really tough to beat Feynman's physical intuition on anything, even if he thought about it for less than half a minute.

[@KiltedWeirdo]

wow. the circle from the plane has collatz 3x+1 effect (its 4 squares is missing its internal circle). the tenis racket is a offset of mass in /2 settings. nice! I wonder. does this apply in quantum and subatomic environments?

[@dianapennepacker6854]

I don't understand how it abruptly stops. That isn't intuitive at all. Due to newtons laws a force in motion should stay in motion. Yet it goes from spinning then changes direction which okay - i gotcha. Yet the fact it stops basically to the opposite direction before ABRUPTLY stopping. While rotating still around the first axis. Then it SUDDENLY goes to the previous direction before stopping again! How. Why.

[@phiefer3]

@@dianapennepacker6854 This was actually explained in the video. The forces that cause it to flip start off small, and as they pull it further from the axis they get larger causing the flip the accelerate, but in the second half of flip they're now moving closer to the axis causing those forces to get smaller, which decelerates the flip. It never stops flipping, abruptly or otherwise. It's just flipping very slowly when it's closely aligned with the main axis of rotation. This is sort of like how when you throw an object up it may seem as if it stops for a moment at the peak before suddenly falling quickly. It never actually stops, it's just moving very slowly that it seems stationary and it's acceleration causes it's speed to increase very quickly.

[@kevinc1956]

Noticed this effect when idly flipping a hammer as a construction worker in the latter 1970s. Always wondered what the cause was, as with some practice I could flip the hammer so that it didn’t flip. Was never sure if it flipped because I imparted a spin. When I went to college in the 1980s and got an engineering degree, I don’t recall that this theorem ever came up in physics, math, or engineering classes. Thanks for the explanation!

[@zoutewand]

It's so funny how many of the reactions are just carpenters saying "oh yeah I know that from when I used to flip Hammers" It's what I know it from too 😂

[@johnnyroman3888]

This phenomenon fascinated me as a 10 year old since I’ve been obsessed with skateboarding, (specifically flip tricks); and although I could not explain it, it was what first got me interested in physics.

[@bradleyries2817]

Interesting point! Kickflips and shuv-its are common tricks, yet the impossible is well....harder to do!

[@rc5981]

it expains why my 360 flips always ended up upside down :-D

[@megashock1319]

@@bradleyries2817 the impossible is my favorite trick and i think tony hawk did a video about this physics property

[@SoroushTorkian]

I’m kind of surprised there aren’t more pro skaters who like physics, it makes logical sense haha

[@Economivision]

I've never been so educated, filled with a learned horror and then so suddenly and gratefully relieved in a single video. You deserve an award for creating the most educational drama in human history.

[@patrickmcleod111]

Well, at least we now know that the Earth has 3 potential axis spin directions........... you know, because it's flat....... Darn, why couldn't God have made the Earth round!!?? Lol 😂

[@andyclark4627]

Wont it have infinite axe's of rotation due to it being a ball??? (Not taking the piss or being sarcastic or trying to sound clever)

[@SmashToBits]

@@andyclark4627 it is sphere-ish. But it is heavier in areas like the gravity image of Mars he showed

[@decidiousrex]

Watch his other videos. He has some seriously cool plot twists involving nothing but science

[@bobrolander4344]

Isn't this just a special case of the butterfly effect?

[@SpaceXForce]

Veritasium: There you have it, an intuitive explanation for the intermediate axis theorem. Me: Rewatches again at .50x playback speed.

[@saggitt]

Brian C The video has to be light and entertaining enough to be popular. You can’t reasonably expect a deep detailed explanation. It was too fast for me as well to get an intuitive grasp on the process.

[@loredan725]

After watching the video, my short summary of the explanation would be "centrifugal pendulum in rotating frame of reference"

[@shnider42]

@divorcedme Whats confusing for me however is what if you were to do the flip over the intermediate axis without any 'little bump'? In such a way that there is no outside forces whatsoever and it was perfectly flipped end over end. Would it still just introduce instability itself? If so, in which direction?

[@John_SalchiChon69]

it was really simple to me /:

[@ArkanoidZero]

@@shnider42 No, a perfectly spun object around the intermediate axis would be stable, the key point he left out is that its like balancing a pencil on its point, its stable, but any small nudge and it falls over. In the real world, such stability is impossible, you will always introduce enough error for the effect to occur.

[@aliasghar_mech_eng9472]

How beautiful you explained one of the most counterintiuitive physics problems in an intuitive way.

[@RIP857]

This experiment is represented in a humorous way in Kerbal Space Program. When in mid air or a vacuum, while EVA, you can perform an experiment where the Kerbal tries to spin a wingnut, but he spins instead. It's not exactly the same thing, but it's really cool to finally learn from where they drew the inspiration for that animation.

[@philiphockenbury6563]

Another KSP fan.

[@dimanyak373]

"The strangest thing is not that it happens, but that spacecraft works without this part"

[@ChrisMcNeely]

lol that's awesome

[@maxcorrice9499]

Did that change? When I played it did this, maybe it’s based on specialty

[@DanielRenardAnimation]

*Russian Cosmonaut spins a wingnut in space:* _"TELL NO ONE OF THIS!"_

[@rdreese84]

That's how the Russians do.

[@axiolot5857]

@@rdreese84 Aaaah those russians

[@Rov-Nihil]

i seriously thought he was gonna use it somehow as a kinetic superweapon, but the earth turning upside down? You really think the US is gonna crap their pants if you can manage to turn the earth around? That's ridiculous

[@clipsedrag13]

@@Rov-Nihil oh no!!! Everything is exactly the same!

[@NicoKupfer]

@@Rov-Nihil Komrad Androvsky, vee kannot tell ze Hamerikans!

[@billdecat855]

So the next time someone calls me "a flipping wingnut" I'll know why.

[@energy_waves]

Gemini

[@mryu1995]

Pff you are such a wingnut

[@billdecat855]

@@mryu1995 lmao, well played

[@Bibibosh]

Bill DeCat why?

[@Bibibosh]

Why is a wing nut an insult? I’

[@FormerlyKnownAsAndrew]

No Earth flip. We good.

[@Krishyadav6668]

😂😂

[@Snaildriver]

There's a theory that the liquid insides of the earth will in fact make it flip, and probably even have already done so in the past.

[@weich1q2w]

This may not be the case actually

[@Snaildriver]

@@weich1q2w That's true, I certainly have no idea if it's the case or not. All I know is that the earth hasn't flipped so far in my life!

[@pestsov]

Well, we may still move some mass to the poles and see what happens

[@steffliot3788]

Hi Derek, the notification of your videos makes me throw all my work away and sit with my tab. You're incredible.

[@svijayiitk]

Me too

[@chinmaykalkeri]

same for me too!!!!!!!!!

[@ScrooVonLoose]

One of the best educators on youtube!

[@eduardotapiasaez]

+1

[@tchgs11zdok15]

😂 I was in the middle of math then I'm like, Me : I shouldn't... My brain : *it's still math only interesting*

[@nathanjohansen7169]

7:45 - "Normally I don't like talking about centrifugal forces." Honestly, neither do I.

[@frostyjhammer]

Always heard that word pronounced "cenTRIFugal" but he's got it "centriFUgal" =`8^o

[@scottmccollum9979]

It's just too rich a subject...

[@karirytkonen5811]

Is there need in this case either? Can't it be explained by inertia as always? Mass tend to continue on it's path and that is why it ends up on wider circular route.

[@scottmccollum9979]

@@karirytkonen5811 I would have to concur...

[@jerrodbates8480]

.....they're the WORST!

[@kennethmccomb7926]

I noticed this years ago flipping a hammer in the air. Each time the head points a different direction. It's cool to have it explained.

[@michaelm.6043]

Me too !!!

[@musicbruv]

And me, used to think it was the way I flipped it.

[@grimresolve2606]

Same, but with a pair of scissors (not recommended).

[@williamrbuchanan4153]

Think it’s about a wing nut in space,nil gravity.. That wing nut spin in space,comes off the thread spinning with its extra inertia.nothing to stop its spin or guide or draw it off its line of original traverse. Not restrained by the thread it has an inbuilt signal of its initial power supply. Having in air on Earth in first use, now it has a atmosphere of the space station. Resistance to the onboard air. Pressure. It gets a build up of resistance and reverses to balance of air resistance. But can’t overcome the power of the thread spinning to remove. Which was excess to requirement for its removal. It is weightless and obey its kinetic energy until it is used by some means of being attracted. It then turned to what ever mass was attracting it as it slowed. The equipment within the space station. Mass attracts weaker mass, if it has freedom to follow the attraction. Snooker ball hit too hard will bounce back and forward in the pocket jaws on Earth and not go into the pocket the rebound resistance has changed its path of drop . It has to lose it kinetic energy at its intended terminal, the pocket.

[@Vary180]

i used to flip things in my hand too, but not a hammer.

[@bjbrooks]

Quite simply one of the best, most fascinating videos I've ever seen. As a tennis player, it's always fascinated me how the racket appears stable when flipped in from a vertical starting position, yet twists in the air when flipped from a horizontal starting position. I've never found any explanation (though to be fair I've not looked), but happened across this from an answer on Quora. Watch the whole video - the implications discussed at the end are quite literally out of this world. Excellent, 10*

[@milosveselinovic1]

I’m just happy there is a scientific explanation for that

[@Protonneutronelectron]

Sve je to ok ali sta je sa derbijem? 😜

[@yatogami7393]

@@Protonneutronelectron Croatian?

[@yatogami7393]

@@Protonneutronelectron kako to misliš reći?

[@Make_Boxing_Great_Again]

Even if there wasn’t, there would still be an explanation, it would just be a unknown explanation.

[@ftnppg1272]

Trump supporters be like, it changes direction because god told it to. Case closed, no more discussion, solved.

[@CoolGuyDoesNothing1]

So technically if we move enough mass from the equator towards the earth poles we can change the rotation axis of the earth?

[@garethdean6382]

Yup, though you'll need to move a lot and countering that masses existing RI will exert a toll too.

[@kanavgagrani9744]

If you somehow manage to take all the mass towards the poles at the same time you will experience the earth flipping gradually on your way

[@alvisvalencia]

Let’s do it

[@Uocjat]

yay! we can finally fix the true north/magnetic north alignment!

[@Oscar1618033]

@@Uocjat love the OCD 🤣

[@Strothy2]

Proving Feynman wrong is one hell of a task... yet he kinda did it ... :D

[@MirorR3fl3ction]

technically Terry Tao was the one who proved Feynman wrong, Derek just reported on it :P

[@Strothy2]

@@MirorR3fl3ction ... well credits to him then :D

[@vsiegel]

He just plain did it. Took me a while to accept that as fact.

[@xapver]

I don't pretend to be a genius, but it took me about 15 seconds after observing the videos to realize, that the rotating objects aren't balanced around the spinning axis. It's nearly impossible to do it IRL. So they have to flip, no way around it. If you are not in an ideal world, where you can apply force to one axis w/o disturbing the others along the way, of course.

[@Nehmo]

@@xapver I have to play these videos at 1.5 so that my fast mind doesn't need to slow down. And I was always having to correct Feynman when he was around. He made so many mistakes.

[@ChrisContin]

It becomes more difficult to travel further in any one axis. Accelerating in one direction of rotation meets this criteria. The wingnut flips because the continuing rotation acts like an acceleration yet with an easy way to change axes from 0 g. The limit as a rational value goes to infinity becomes irrational in the same axis, every time. Nice video!

[@paulomanuelsendimairespere3901]

Mechanical Engineers found out many years ago that the best approach for dealing with real problems intuitively is to consider inertial forces. Otherwise, you get lost in a massive amount of equations.

[@rohitchachlani9539]

enter flywheel effect

[@KozmykJ]

I first observed this phonomenon 54 years ago when I was juggling books, as one does, especially at age 10. I asked again and again over the years what caused it. My parents, teachers, anyone who'd listen, No one ever had a answer. Most had never noticed it happening at all. I'm sure knife throwers must have figured how to predict it even if they didn't know the cause . Well. thanks to Veritasium, if finally got my answer last year, in 2019. 🖖

[@kurtreber9813]

I too flipped books and now that you mention it, I HAVE noticed this turn during flip. I just assumed I wasn't balancing the book very well to start.

[@wonderingalbatros3603]

@@kurtreber9813 Ditto. I'm high IQ, ADD as f$%k and embarrassed to admit I didn't question a single thing.

[@christopherconner6151]

I saw it happen as a child, saw that there was no " explanation " shrugged my shoulders and continued to twist flip things to see it's center of gravity so I could educate my self without books and others telling me their point of view. Lol

[@KozmykJ]

@@wonderingalbatros3603 I'm only 95th percentile ... a bit thick really 😜

[@glenapfelstadt287]

Ya know, some read books and others realize physical phenomena as the books fly through the air.

[@johnchessant3012]

The tennis racket theorem is so cool. I saw it in my mechanics course years ago and it is still fascinating to me now.

[@daltoncook3009]

I know right! I have always flipped things like that and never new why they would spin like that. I always thought I was doing something with my wrist to cause a spin. I feel a little less special now that I know I’m not a wrist twisting master of tossing things and it’s just physics.

[@marshallc6885]

dalton cook there should be a machine that will flip it perfectly just to see if we can do it with it half turning

[@TeatroGrotesco]

Watching a mathematician do something physical and coordinated is almost as interesting as the great info provided.

[@ernestolula3280]

Grotesco... ¿Teatro?

[@EtanChamare]

So if we dug up a bunch of mass around the equator and put it on the poles, we could get the earth to flip sideways?

[@iwasbornfriday]

maybe thats why the earth flips its poles.

[@gJonii]

That's a neat plan. Unfortunately, you'd have to fight against gravity.

[@Anvilshock]

Please note that "bunch of mass" also includes the Moon.

[@Charles-fc9gi]

No, it would be like spinning the tennis racket on the long (stable) axis. So to flip earth i think you would have to put the mass at 45° between the poles and equator. And as high as possible. Or if you put it on one pole that would work, but not both.

[@malachipeterson9661]

Most likely

[@wlodell]

As a boy I could never get my tennis racquet to spin evenly whenever I tossed it in the air. I was obsessed and frustrated by that. Fifty years later, now I know!

[@markgomez3688]

You're never to old to learn, you can teach an old dog new tricks. A wise man once said.......

[@samfreed7251]

@@markgomez3688 TOO, with TWO O's, TO be exact.

[@markgomez3688]

@@samfreed7251 So what!... It's not like i am writing a letter to the Queen... oops Queens speech is on now , must go....

[@WarPigstheHun]

Basically fulcrum crowbar on invisible fulcrum crowbar.

[@itshappeningla4t86]

🤣

[@Gaswafers]

The goal of this video is to prove Feynman wrong. *8 minutes left.*

[@DobromirManchev]

Lol, i did the same thing! When i heard that i paused the video to check the time remaining. :D

[@_BangDroid_]

Well I don't think he succeeded, it's not very intuitive at all

[@kristinejoybueno8102]

Ow ma god ur incredible

[@josephcope7637]

This is a concept that's somewhat difficult to comprehend intuitively ... like Euler's Identity.

[@przemekolchowy8745]

@@_BangDroid_ Isn't it? Like, it's basic stuff tho. Average high schooler should get it without any problem...

[@ismaelabufon1696]

Spent all my teenage years playing with the tv remote, flipping it on the air and noticing the flip. I never asked why I couldn't flip it vertically without it turning. The trick for me was to throw it higher, so it would turn 2 times, so I would catch it how I threw it. Similar with phones when they came around. Then, older I became a bartender for a while and while flipping bottles and stuff (flair bartending) I sometimes noticed the same thing as I would try to get the label to face "forward" when the bottle landed on my hand. You just solved a mini life-long question that I had hahahaha.... kudos! (I was getting a bit judgemental when you mentioned proving Feynman wrong -- "this guy is cocky" hahaha... but then you brought Tao into play and it was all good 🤷🏻‍♂️😂 -- and anyways, is still a bit cheating as Feynman didn't have all the 3D bells and whistles we have today)

[@khpsphysicsmathematics8277]

Hmm u r R8 actually feyman thought on this only for 15 second thats not fair.

[@wampaku2]

I noticed this too in my teenage years with the remote. I asked everyone I could think of if they knew why. Parents, science teachers, etc. Nobody could provide an answer.

[@1DusDB]

Also me haha !! - noticed the flip since school days with my ruler and since then always tried with rectangle shaped things

[@nate_storm]

Flipping TV remotes is incredibly entertaining

[@craigfenson]

or it could also be that feynman perfectly understood the phenomenon, but since he was asked about an 'intuitive' explanation whilst knowing the difficulty of getting it across in a simple manner, he just said no.

[@aviatordude1961]

I thought the reason the Russians kept this a secret was going to be so their female gymnasts would always win gold!

[@kimvangvideomarketerbangko3265]

Hah! Underrated comment

[@narrator206]

Agreed

[@Icerecruit0]

I mean their olympic athletes were at an advantage anyways for other reasons

[@aozzya1563]

@@Icerecruit0 What advantage? I don't really keep up with Olympic stuff sorry.

[@Icerecruit0]

@@aozzya1563 the Russians aren’t allowed to compete as “Russia” anymore because they used steroids lmao

[@Machtyn]

The crazy thing is, skateboarders, specifically, Rodney Mullen, intuitively knew this when he developed the "Impossible" skateboard trick back in the 1980s.

[@yoda2661]

The best one. Ever.

[@DL-kc8fc]

No. They attributed it to air resistance.

[@starmc26]

No.

[@French20cent]

You also watch Physics girl don't you :)

[@Machtyn]

@@French20cent On occasion. Actually landed on the Mullen - Physics Girl episode on a Tony Hawk youtube bender.

[@Kaldrin]

So this is what happens whenever I flip the remote and it does a half spin

[@justArandomfellar]

Yeah 😆

[@sonorousguitars2670]

I experienced this with a racket when I was eight in 93’ and couldn’t explain it. My neighbor told me to stop smoking dope when i told him..........well screw you Carl!!

[@laxminarayanbhandari855]

Lol

[@uhmmm2110]

@Carl Glennerster LOL!

[@devilliar3786]

Nice fib, bro.

[@pootis9180]

i dont smoke no lope

[@caesaraugustus8281]

Lmao

[@TH-wr1dv]

Yay I like much that Vertasium is back at interetsing but not so popular topics.

[@Snooker-cn3dm]

yes very interenetsing indeed

[@NLTops]

Someone should tell the Flat Earthers of the Dzhanibekov Effect. They'll freak out and think that sooner or later their precious disc world will flip and they'll all fall off.

[@joolslaloosh]

Not necessarily, but this effect does correctly explain why the stars rotate in the opposite direction in the so-called southern hemisphere.

[@NLTops]

@@joolslaloosh There's a new update out for your sense of humour, don't forget to download it.

[@wonderfurret8223]

@@joolslaloosh Flat Earther Physicist: So you're saying that the direction of spin on these stars depends on where you observe them? This is some serious quantum physics...

[@1SpudderR]

NLTops Hmm? It appears that quite flatly you have to acquire the correct perspective, which revolves around the “Absolute!”

[@NLTops]

@@1SpudderR What are you trying to say? I don't follow.

[@wassenaat]

always nice to see a video that does rigid-body dynamics more justice than my faculty

[@saklaniaditya]

Coincidence: Just started to learn about Moment of Inertia in school. This helps man.

[@saklaniaditya]

TY for the heart.

[@benjaminshields9421]

It's like mass, for rotation. In other words, how easy is it to change the object's rotation

[@deba123ful]

Landau and Lifshithz man.. refer to that book.. that is gold

[@duuhdboui2920]

They're listening

[@Anvilshock]

This helps man, this helps animals, this helps rock, this helps universe … Let's eat grandma.

[@Sigmatica]

People: They hid it for 10 years! Russian: Chill down I just forgot about it.

[@davidgumazon]

Anime Universe: Tusk Act 4!

[@slaughterround643]

"chill down"

[@anandtewani7591]

why the hell did my mind read the second line in russian accent

[@zyern2822]

@@slaughterround643 sounds Russian

[@davidgumazon]

@BlazarBlue Use Toilet Paper for Napkin!

[@radicalrick9587]

I wish this guy was my science teacher back in Elementary School, Jr High School, High school, etc..

[@Bollibompa]

And this is why being a teacher should have high status in society. Unfortunately, the need for a high quantity of teachers often far outweighs the possibility to keep the quality high. An interesting sidenote: Many esteemed physicists and engineers switched to teaching high-school science in their later years. Imagine having a nobel laureate teaching you about forces and moments in ninth grade...

[@markwashington2412]

Bollibompa that exactly what happened for my grade nine math class. A former nasa astrophysicist taught us about the slopes of lines lol.

[@001vgupta]

I too would have enjoyed him, as my teacher.

[@kennethkline7702]

Actually, your science teacher was probably a lot like this guy. You were probably just an immature kid that can high school who wouldn't have listened to anyone, regardless. Unless you were the type that watched mr. Wizard in which case you would have thought your science teacher was cool anyway

[@markwashington2412]

Kenneth Kline sorry what?

[@stevenmccrickard1401]

New sub, thanks for the content. I found your video interesting, informative and entertaining. I experienced this many years ago when I was a carpenter stacking roofs. Showing off I would spin my rigging axe and catch it, it looks dangerous and quite impressive especially with the twist. In reality it is quite stable and predictable.

[@btallred]

Oh..., that’s why the bread always lands butter-side down.

[@badusername9903]

you bread spins when you drop it? wish my bread was that cool

[@gorn9161]

Best clinical experiment: Tape toast, butter-side up to cat and drop them from height.

[@Miss_Giggy]

That's Murphy's law.

[@joaquintakanaka]

That happens because it's heavier on the butter side, that's all.

[@joaquintakanaka]

@@DNVPIVIN It is heavier than none 😉

[@YeppyNope]

"Mathematicians, Soviet Secrets and the End of the World" Woah there, slow down buddy.

[@kiplavin]

title for a REN-TV shows

[@vsiegel]

He just got up to speed for the bold move: Proving Feynman wrong.

[@Falcrist]

I have a friend in Minsk Who has a friend in Pinsk Who's friend in Omsk Has friend in Tomsk With friend in Akmolinsk His friend in Alexandrovsk Has friend in Petropavlovsk Whose friend somehow Is solving now The problem in Dnepropetrovsk...

[@benjaminshields9421]

Hey, Vsauce! Michael here! What did one of the best mathematicians have to do with Soviet secrets? And when is... the end of the world? *cue music

[@milanstevic8424]

@@benjaminshields9421 (•_¬)

[@alphapotato_gd9597]

Mum: “so what did you learn today?” Me: “it’s spinning about its maximum moment of inertia”

[@Julian-qs8jy]

Why isn't the explanation for the intermediate (y)-axis in 8:28 not equally valid for the x-axis. A small inclination from it should give the same periodically movement in my view, the only difference is that now the mass ratio between the main rotating mass and the tilted is different... Any ideas about that? I would appreciate it :D

[@Yalikejazzboi]

This explains everything, the Russians have been rotating me a 180 degrees during my sleep.

[@MarkAhlquist]

I don't get it, but I like it.

[@theev3436]

😂😂

[@mcxhalo]

You win.

[@engineerauthorpilot]

I just liked your comment to bump your "like" stat to 666. Was it the Russians that somehow compelled me (subconsciously) to do this or was it Satan? Or... are Russians actually Satan?

[@Anvilshock]

@goodperiodictable.com Reported for spam.

[@ThoughtinFlight]

I had advanced dynamics for my masters, and this was the best explanation I have ever heard.

[@GuidoCostantini]

We finally know why the butter and marmelade side of a toast always hits the carpet.

[@789563able]

But why does the bottle always point to the ugly girl when I spin it?

[@ragnarok7976]

Bro, lemme introduce you to laminate. All the easy clean up of hardwood at the cost of carpet 😉

[@GuidoCostantini]

@@ragnarok7976 only those who haven't set foot on a real Persian silk carpet can think tgatc and laminate can be put side by side in a comparison in anything by a distopic universe

[@DillonLeBlanc14]

Bro why do you have carpet in your kitchen?

[@GuidoCostantini]

@@DillonLeBlanc14 I'll let you know, people do eat and have tea in the living room, for how amazing that might sound

[@mgwrzer]

Dumb question, At 10:14, the Earth flips over, AND the rotation reverses. Isn't supposed to continue spinning in the same direction as before the flip?

[@JimOHalloran]

Terry Tao was in my year 10 maths class! Starting sometime mid year, he used to come over from the primary school a couple of times a week, sit in our high school maths class. After about 6 weeks of this he was done with year 10 and moved on to year 11!

[@bengunn3698]

@Robert Ratskywatsky I went to school with einstein ,never understood why everyone raves about him the thick bastard was in ''d'' class while i was in ''b''. ;;A;; was top of the grade in those days.Little Jimmy Einstein i remember him well.

[@garethb1961]

I taught physics to Terry Tao at a university when he was 9 years old. Back then he was just a freak kid to me. Interesting to hear him being described as the greatest living mathematician. I don't think I paid him that much attention back in the day. He was just a kid who, in physics labs, had trouble with the stools, because his feet didn't reach the floor. This was Flinders University, by the way.

[@JimOHalloran]

@@garethb1961 Yeah, my memory is much the same. He was obviously a smart kid, and likely to do something important, but greatest living mathematician is high praise indeed. I was a student at Blackwood High School at the time, literally just up the road from Flinders Uni.

[@andrewmerrick601]

I absolutely loved this video. You are filling the void in my heart that Vsauce left behind.

[@iwanttopk]

he went to youtube red. I stopped watching after that.

[@samharper5881]

And Derek knows the difference between lay and lie anyway. VSauce did not and this is not acceptable.

[@shubhamkanauji7261]

Whyy ? Vsauce is not making videos anymore ?

[@mwperk02]

@@shubhamkanauji7261 well its a youtube red channel now but he does upload to the ding (formerly dong) channel vsauce 2 and 3 upload as normal.

[@joesterling4299]

@@mwperk02 And that's when I'll watch him. As far as many of us are concerned, information behind paywalls doesn't exist. If it's important enough or interesting enough, someone will put it out there for free.

[@Hakasedess]

My question after watching this, though, is "How much mass would we need to dump at the poles to make the earth flip 90 degrees?"

[@mikemondano3624]

The questions asked show just how deeply deluded people are who say they understood the video.

[@awfuldynne]

​@@mikemondano3624 Going by the abstract "disk with point masses on it" example, we'd need some parts of the equator to have a different mass than other parts for Earth to be in danger of flipping 180°, right? (e.g. the two quadrants centered at 0°W and 180°E are more massive than the other two centered at 90°E and 90°W) But that's a 180° flip. Hakkapeele asked about a 90° flip which would put the current poles on the new equator and the new poles somewhere on the old equator. edit: posted before finishing the video. The poles would need to have a mass between that of the light equatorial quadrants and the heavy ones to make Earth's rotation about its intermediate axis rather than the one with the greatest moment of inertia. Also, I've been using "mass" where I should be using "moment of inertia".

[@mikebeam822]

no, the question is - how much mass(ice) has to disappear before we flip?

[@Asagofficial]

@@mikebeam822 Well, if you reduce the ice, water from that ice, would move to equator. Witch, would simply slow down the spinning. But if you would reduce the amount of water on equator, and transfer it to the ice and put it on the poles, than there is a possibility of flip. But even if you melt, or froze water. The mass of the planet is still the same. So its not really possible. You just change where the mass is. But if you could add more Ice/Water on the planet or transfer out of the planet, than you can change its rotation.

[@mikebeam822]

@@Asagofficial Let me ask you this, remembering that, as a planet we go through periodic ice ages - which weighs more ice or water? If ice weighs more, then, as the polar ice caps re-freeze, which we can easily assume is true, weight(water) will move from the equatorial regions freezing and condensing at the poles. Correct? Leading to the flip.

[@CorwinAlexander]

Thank you. I wondered why the intermediate axial theorem didn't appear to apply to the planet. Thank you for clearing this up.

[@mickeyg.c.1654]

It's amazing that you're capable of making a guy like me understand physics clearly. Thank you so much for uploading this video

[@ChristopherWeiss]

"The goal of this video is to prove Feynman wrong." Immediate thumbs up for that one. :D

[@BAGG8BAGG]

That should have been the title, instant hook there.

[@Somethin_Slix]

Why do you have a verified account account with only 7 subs? Genuine question!

[@ChristopherWeiss]

@@Somethin_Slix Why does anyone care about this? I think it's because I was an early adopter of Google+ which no longer exists.

[@Somethin_Slix]

@@ChristopherWeiss I cant speak for anybody else but I've seen many other accounts with the check mark and very few subs and I've always just been curious. You get hounded about it often, huh? Lol cheers!

[@ChristopherWeiss]

@@Somethin_Slix Anytime I comment someone asks about it. What's the big deal?

[@zeekjones1]

Over 300 people broke their phone after watching this video.

[@rubiks6]

I wasn’t one them but thanks for the laugh 😆

[@randomuser5443]

I’ve flipped my phone so many times

[@a.gabbey5569]

Not when you tried it on your bed

[@TeeTipu]

Start a WhatsApp warning message then. :D

[@radastir]

I broke my washing machine

[@진윤호-w5p]

What an amazing explanation!!! Thank you for your great work!!!

[@lamboqin2180]

Veritaaium: The earth is stabe. V-Sauce: Or is it?(raises eye brows)

[@Goldrusher-ee3jo]

"Kid maker" Hmmmm

[@LukeMXack]

you can hear this comment

[@LoneBeastYT]

I literally heard vsauce theme music dude

[@ThatUnknownDude_]

*SCIENCE BATTLE INTENSIFIES*

[@pawan235able]

but what if we could somehow make the earth unstable??? we all would be flipping :D :D .... need to find a flipping planet in the space and we would find alien life, cuz who doesn't want free joy rides??

[@Monkeyheadtpc]

So... if we put huge weights in arctica and antarctica, we could make the earth flip?

[@sanderkleinbreteler]

No, because it is still liquid inside. It would then start spinning at a 90 angle. So half a flip...

[@the_original_Bilb_Ono]

We could use the dead useless weight of all the flat-earthers.

[@dtonorth8122]

Earth is cube

[@HuntersMoon78]

@@the_original_Bilb_Ono Good answer

[@anantsingh1049]

Dats illegal

[@KiemPlant]

Man! I've always wondered why this happened when I flip the tv remote like that.

[@tooba6290]

Me too.. I obsessed with spinning things

[@Toolmamon]

Yes!!!! Me Too!!!!!!!!

[@YostPeter]

I always thought I just had some mundane skill.

[@SolvayConference]

Wait, so if there is no "bump" then would it not exhibit that effect at all?

[@jdzamora97]

SAME!!! I've been doing it since I was in high school and I thought it was weird and amazing

[@jacobpoulton3547]

I've watched this video like 5 times and the hook at the begging is so good I still watch the video the whole way through

[@t.pisani8239]

I always thought I intentionally flipped my tennis racket like that.

[@dhy5342]

You do induce the spin, whether intentional or not. when the racket leaves your hand a small rotation is imparted. This is clear in the video although not mentioned or acknowledged.

[@Stan_in_Shelton_WA]

My condolences!

[@0fflineXD]

dhy5342 he does, at 8:24 He just doesn’t say it straight out as you want to hear it, When you say “a small rotation is imparted” He says “what if the disk is bumped, so that it’s not longer rotating perfectly about its Y axis”

[@Yamaazaka]

@@0fflineXD Well nothing in physics in this universe is perfect. A perfectly spinning object like the demonstration can only exist in theory. So "a small bump" is everything normally, essentially.

[@0fflineXD]

Sol Ascending ik? I just answered the guy

[@rutvikpanchal466]

Smarter Everyday : Laminar Flow! Veritasium : Theorem of intermediate axis!

[@yugal.prakash]

ok

[@hajmola7605]

Hello ding dongers

[@theCodyReeder]

Oh! so thats why my liquid filled bullets keep tumbling!

[@nightmareinaction629]

Cody'sLab ummmm interesting

[@mokshdhawan1966]

ay look it’s cody

[@xavieryates9782]

Chances are, only an American would think of bullets...(my excuses if you're not American)

[@randomly47]

Bullets. Never heard that one coming.

[@MrDickfish]

Your bullets tumble because you ruined the Ballistic Co Efficient

[@Schugi2]

I actually discovered this behaviour on my tennis racket and was wondering why for years. Thanks for the explanation !

[@mattysheppy1193]

This is literally the back bone of skateboarding flip tricks

[@davidnudell7916]

Yy

[@roku_nine]

Rodney Mullen was interviewed by dianna of physics girl about the intermediate axis theorem

[@ClarkKant1]

Well, not "literally". It's not an actual backbone. That would be just weird.

[@TheB1RDY100]

@@ClarkKant1 Yes it is a backbone. its the Backbone of skateboarding, literally. Matt said it is and i believe him.

[@irok1]

@@TheB1RDY100 it's someone's spine? That's what the person above you was saying

[@clampfan101]

Student: Can you make this intuitive? Richard Feynman: ...No. Terry Tao: Hold my beer.

[@richardmccabe2392]

"hold my wingnut"

[@rongarza9488]

As soon as I heard Richard Feynman, I knew it was going to be a smart-ass reply.

[@AgustinusLaw]

@@rongarza9488 Does actually being smart negates smart ass-ness? Feynman is one heck of a smart dude.

[@ekkehardehrenstein180]

Proceeds to use an animation to make it "Intuitive"

[@robertnett9793]

@selphie Wingnuts I assume?

[@deltanebula8622]

I like this older style of video from Veritasium. Thanks for just an interesting science video!

[@michaelggriffiths]

Flipping brilliant!

[@memetoo1002]

I see what you did there.

[@josephstalin7995]

That's great and all, but why is there a baby bottle on the ISS?

[@AnonEMus-cp2mn]

Baby bottles are used so babies don't spill their drink, and apparently also used so microgravity doesn't "spill" the astronaut's drink.

[@josephstalin7995]

@@AnonEMus-cp2mn yeah, but the opening, as well as the bottle, is tiny. There are many 'adult' alternatives for 'unspillable' drink bottles. Also, if I'm not mistaken, most drinks on the ISS, as well earlier space stations, are served in resealable baggies similar to a capri-sun.

[@lioraselby5328]

Because one of the astronauts is into ageplay

[@Jonbug1]

@@AnonEMus-cp2mn But why launch babies into space? It seems irresponsible...and where are their mothers??!!

[@Jonbug1]

@@lioraselby5328 Yes of course! We would be good friends...SICKO!!

[@HowI_IKnowme]

I do construction, and I've been doing this with every hammer or pry bar I've picked up for ten years. Feels weirdly satisfying to finally learn what it's called.

[@jamest.5001]

I'm no mathemagician, but I could watch examples of this all day!!

[@adityapathak5761]

Mathematician*

[@milanstevic8424]

@@adityapathak5761 *wooosh

[@charlesfreeman9917]

@@adityapathak5761 I'm thinking they meant a contraction of math and magician rather than mathematician, but I could be wrong...

[@frankyvee1]

He may have been inserting some magic humor into his comment.

[@onetrueslave]

@@milanstevic8424 In there defense, thairs a lot of people out here who've mispelt things. See?

[@RobertSimpson-wp3pr]

Ty for this, you truly are a very good teacher.

[@johnknoefler]

As a kid I loved to flip objects and spin them. It drove me nuts when some times didn't cooperate. I always thought it was kind of me doing it wrong and only realized that some objects are harder to get a good spin out of. Now I know why.

[@giridhar6089]

Derek... Just letting you know how we are all forever indebted to you for these awesome videos and explanations. Thank You, Sir.

[@ScottSteinhart]

I wholeheartedly agree with Giridhar. The information you present is both interesting and entertaining.. Thank you for your hard work in producing these videos!

[@ScottSteinhart]

@Tech Stuf With all due respect, you are most certainly entitled to your opinion. That said, however, it's really non of our business what he does or when.

[@nos464]

☺ good

[@rollbocke]

@Tech Stuf You're trivializing global warming and all its horrific effects by tying it to your 'movie critic' review. And global warming has to be an assumption since you don't to go beyond generalized terms (late hour), (most critical juncture in human history) instead of the stating the subject matter itself. Who addresses a serious topic without even identifying it? You're no Greta Thunberg.

[@ThomasSteinbacher]

The thing about the flipping wing nut was cool, but the thing about bodys that change their axis of rotation due to dissipation was really an Aha! moment: Kinetic energy could change while angular momentum stays constant.

[@alanthompson4912]

I wonder if it has to do with change of water displacement and lava displacement in the earth due to gravitational rotation and whatever is going on in the middle of the planet.?

[@dirks4093]

He says the Earth is stable and won't flip... but I'm gonna keep my phone's screen auto-rotation on (just in case).

[@BrotherAzrael]

Misread this title as 'The Bizarre Behavior of Rotting Bodies, Explained', here I thought I'd have an explanation as to why cadavers misbehave.

[@benzminibusdoc]

45 behavior can't easily be explained, too erratic

[@reginaphalange4182]

LMAO!

[@FrVitoBe]

all the covid dead coming back?!

[@andrewherman2537]

@Roger Felton it's your epididymis that gets tangled up! Ouch

[@shotor9828]

This explaination is beautiful when you're actually learning this stuff in school... keeps me wanting to know more. Thanks Veritasium!!!

[@jamesbarrick3403]

I have experienced this my whole life - mostly flipping a tennis racket also. I would try over and over to flip the racket without it making a twist... I could not do it that way. I figured it was involuntary twist from the momentum or release from the forced of my hand. The math is light years above my head, and to be honest the explanation at the end is as well. But just the explanation that you have the 3 axis and they are not balanced and they influence each other kind of makes sense to me. Still this blows my mind.

[@tarik9563]

maths are not that hard. it's like a dance and you just have to practice it. well if you want to understand the math-geometry explanation, then try to rotate the tennis racket while puting your fingers on the bottom sides or the axis of which you want to flip and then you'll understand by the feel.

[@antonystringfellow5152]

You'll never undertsand it from the maths. Not even Feynman could, which is why he couldn't explain it intuitively. If you watch it again James, you might get it. It's much simpler imagining the centrifugal effect. If it was possible to spin the object with the weight at the ends of the spin axis perfectly positioned, it wouldn't flip at all. So, in theory, it's not impossible to do but it probably is in practice. After all, perfection doesn't exist.

[@sebastianbogdan9011]

I don't know about you ... I can , always did ... never failed, just add the counter spin. It will always spin on your desired axis.

[@christaphersimmons2216]

@@sebastianbogdan9011 so you can do it when you counter the exact base parameters of the test

[@insidetrip101]

"I figured it was involuntary twist from the momentum or release from the forced of my hand." Someone please correct me for being wrong, but this seems to be exactly the explanation given. At 8:22 : ". . . what if the disk is bumped so that its not longer rotating perfectly along its y axis" That seems to me to indicate that this is similar to balancing a pencil on its sharp end. Any small deviation from perfect balance will cause the pencil the top of the pencil to accelerate to the ground, which causes a larger deviation, which causes the pencil to accelerate faster, and it repeats until it makes it to the ground. Accept in this case, the "pencil" is a disk, and it can't hit the ground. Instead it flips over, does a complete rotation. Going back to the pencil, imagine that it weren't to hit the ground, but completely rotate, then as it was perfectly inverted it would have its maximum amount of energy (like a ball rolling down a hill and up into another one). After that, then the pencil starts to lose energy as it rotates back to make a complete rotation (like the ball rolling up another hill after rolling down the first hill). As a result, it'll slow down back to where it was when initially flipped, and then build back up speed as that ever-so-tiny deviation did in the very beginning. So would be the same case with a disk. But please, someone explain to me where I'm wrong. I really don't think this is correct, because if it were, then I would think very small forces (such as air resistance) would create irregularities in this flip, and it appears that this is not the case.

[@Ashalmawia]

I've actually thrown a tennis racket and other similar objects like that before and knew this effect well without actually realizing it was something important.

[@starz2114]

i showed this effect to friends with my phone we all kept being amazed it flipped over upside down and we had no idea why

[@cosmicHalArizona]

Ya knew something screwy was going on.

[@UnIvErS8uL]

This is the best explanation, thanks Derek

[@rodneybowie8087]

I never could get my remote control to flip "flat." I'm glad astronauts & scientists also can't do it.

[@ryanwilson5936]

Just compensate for the flip before you toss it.

[@Postermaestro]

@@ryanwilson5936 good luck with that

[@ryanwilson5936]

@@Postermaestro I’ve been doing it since I was a child. Try it. All you’re doing is creating an opposing force strong enough to overcome the natural flip.

[@jimybrooks6055]

I can use my feet to do this with a skateboard although I guid the skateboard with my lead foot which is an outside force for the board flip around …. Hard flip!

[@TheB0sss]

@@ryanwilson5936 dude, it doesn't work like that, you could do it by accelerating the natural flip, but an opposing force does not work Since it will just flip the way you rotated it in. It's the same axis

[@briang8766]

Many of these spins take me back to my old skateboarding days! 180 & 360 degree kickflips, heel flips, pressure flips, etc.

[@p.as.in.pterodactyl1024]

A skateboard has 3 different moments of inertia around its 3 principal axes, too! Lol.

[@DavetheUberSlave]

"Normally I don't like to talk about centrifugal forces" lol

[@tigerchills2079]

totally understandable statement :)

[@proliferatingprofligate7032]

"Not since _the incident,_ anyway"

[@rubensanchez8118]

Ah yes, the great centrifugal force dilemma of ‘89. How could one forget?

[@jasensthename97]

@@rubensanchez8118 This is my favorite sector of KZbin ^

[@robohaul5048]

Can someone please explain the bump mentioned in 8:25. If there is no bump like that mentioned here, can we not observe Intermediate axis effect?

[@PmFlinty]

Not if the object is spinning perfectly on the axis with perfectly centred mass I think.

[@tobiasyoder]

I can see Derek has been watching a lot of 3Blue1Brown lately lol

[@NourSelim0]

From the description: "Special thanks to people who discussed this video with me: Grant Sanderson of 3blue1brown" 😁

[@trespire]

I prefer Red Green.

[@spg890]

exactly what I was thinking

[@stevethea5250]

@@NourSelim0 timestamp

[@NourSelim0]

@@stevethea5250 It's in the video description, not the video itself

[@jepbrown4941]

Whenever I feel stupid, I search some of Veritaserum’s video, lifted me up… when I feel too smart, I search some of Veritaserum’s video, kept me grounded.

[@Stray0]

_clicks video_ "the earth won't flip upside down" _visible relief_

[@BRBearUSA]

I always thought tennis players were intensionally flipping their rackets... LOL.

[@VNeto94]

I do this with the remote controller whenever I'm bored watching TV until the next episode of Pawn Stars starts...

[@dashriprock337]

It's physics

[@dashriprock337]

It's everywhere lol

[@Axiom_Dominus]

We're instinctively playing with and understanding physics when we do this and how we haven't noticed til now is sad but empowering.

[@jondunmore4268]

And to think that every time I flipped a tennis racket, I thought I was doing it through free will. This video tells me tennis rackets have souls and are flipping themselves.

[@carolduvall111]

Oh my you already got a list you are working on thanks for sharing your knowledge and a bit of fun