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/10.1007/BF01049489
Janibekov’s effect and the laws of mechanics
Petrov, A.G. & Volodin, S.E. Dokl. Phys. (2013) 58: 349. doi.org/10.1134/S102833581308...
Tumbling Asteroids
Prave et al. doi.org/10.1016/j.icarus.2004...
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/10.1137/070704393
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 KZhead 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.
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!
You just got defective hammers.🤣
@@johnpossum556 additional evidence: rip claw configuration in hammers produce more consistent axial twisting.
Once again ball pein better than claw hammer. 😀 😉
@@joedaly6887 that has been my experience flipping a straight claw for years--it never rotated about the intermediate axis. Very east to flip
Yeah. Same here. Carpenter. Hammer. Flipping.
"Babe, come over, im home alone" "No, babe, Im solvin a centuries old math problem."
The problem: Where does she want to go for dinner.
What a chad, keheheh.
You’re dating the wrong person if this isn’t an acceptable alternative to dinner
He bumps her on the secondary axis to get her to turn around
@@TheNebulon it's the 3rd axis we all want
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!
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.
@@nramrez Oh.. could you tell me then please?
Time to convert some of that inertia to getting a job 🙂
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.
what question?? im curious and havent read much feynman
@@jaydenwilson95225:51
@@jaydenwilson9522 it’s in the video
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
@@jaydenwilson9522 wow, I guess you are smarter than Feynman
*Russian Cosmonaut spins a wingnut in space:* _"TELL NO ONE OF THIS!"_
That's how the Russians do.
@@rdreese84 Aaaah those russians
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
@@silverhawkroman oh no!!! Everything is exactly the same!
@@silverhawkroman Komrad Androvsky, vee kannot tell ze Hamerikans!
I've been flipping tennis rackets for years and never been able to get my head around this effect. Incredible.
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.
I always assumed it had to due with imbalanced rotation compounded by air resistance. Which I guess was half right.
Was this a Head, tennis racquet by any chance? 😎
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... ;(
David King I always thought it was my skill that caused the flip I didn't know it was doing it on its own 😕
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.
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?
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
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!
Wow! You have sold me! I'll watch it again!
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
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 ?
@@danielhope2924 very good point. Time For me to go research exactly how much ice is estimated to be Frozen.Thanks for the input
@@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.
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.
aww that's so cool
"He concluded that his wrist was subtly imparting spin." Well, as we've learned in your video, your dad was right
Cannot tell you how many hours I have done this with a TV remote too, trying to get a straight flip. Futile all along.
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.
@@siggyretburns7523 Yes that is correct, if it were perfectly balanced, it would not happen. But there is no such thing as "perfect" in practice.
No Earth flip. We good.
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!
7:45 - "Normally I don't like talking about centrifugal forces." Honestly, neither do I.
Always heard that word pronounced "cenTRIFugal" but he's got it "centriFUgal" =`8^o
It's just too rich a subject...
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.
@@karirytkonen5811 I would have to concur...
.....they're the WORST!
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.
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
@@lukeernst2101 if air is causing this misalignment why do we still see this effect in space ?
@@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.
@@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.
@@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.
How beautiful you explained one of the most counterintiuitive physics problems in an intuitive way.
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!
"The goal of this video is to prove Feynman wrong." You have high ambitions, young man!
As soon as I heard him say that I came to see this comment. Was not disappointed. High ambitions, indeed.
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.
I think he was quite successful. Raspberries to Feynman.
@@raykent3211 Indeed, it all depends on what you call "intuitive". I think inertia is a step higher than what most people will find intuitive.
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.
So the next time someone calls me "a flipping wingnut" I'll know why.
Gemini
Pff you are such a wingnut
@@mryu1995 lmao, well played
Bill DeCat why?
Why is a wing nut an insult? I’
I had always wondered why a tennis racket could never flip straight, finally get an explanation! Thank you lol
Thank you! This is an amazing explanation and I can finally see in my head how it works. I've never been able to follow the maths involved.
Video: contains the phrase "prove Feynman wrong" Also video: doesn't use this phrase as clickbait. I salute you.
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.
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.
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.
"prove Feynman wrong" is not working clickbait - it's so obviously spam that nobody would click it. And then... he actually did what?
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.
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!!!!
anxious minds made modern world possible
First thing that occurred to me too. Been a carpenter for many years. Hammers will do that every time you flip them.
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
@Alexandre BrunetI hope so
@Compliment Thief Stop thieving.
Watching a mathematician do something physical and coordinated is almost as interesting as the great info provided.
Grotesco... ¿Teatro?
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*
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.
Another KSP fan.
"The strangest thing is not that it happens, but that spacecraft works without this part"
lol that's awesome
Did that change? When I played it did this, maybe it’s based on specialty
This is the content I subscribed for. Well done!
Agreed
So this is what happens whenever I flip the remote and it does a half spin
Yeah 😆
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.
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.
Me too !!!
And me, used to think it was the way I flipped it.
Same, but with a pair of scissors (not recommended).
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.
i used to flip things in my hand too, but not a hammer.
This explaination is beautiful when you're actually learning this stuff in school... keeps me wanting to know more. Thanks Veritasium!!!
Never been a more deserving like to a comment on a video!
@@Tattootin :)
I watch this as a break from stupid school work.
@@llll-lk2mm %ï
@@mapk4655 Good
always nice to see a video that does rigid-body dynamics more justice than my faculty
That was interesting and really intuitively explained. Thanks!
There is also a skateboard trick called the impossible flip because of this. They counter it by leading the front foot trough the flip to keep it from flipping on the other axis.
yeah thats exactly what i was thinking and i was like-wait are they defying this theory?
I saw the physics girl video about that.. but I understood that here..
kzhead.info/sun/rKqLgMyhZ5yeeps/bejne.html
this effect is also what makes the 360 flip (tre flip) work the way it does.
yes! this took forever to learn. btw using the front foot to balance the board is a "front foot impossible." An impossible uses the back foot.
Veritasium: There you have it, an intuitive explanation for the intermediate axis theorem. Me: Rewatches again at .50x playback speed.
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.
After watching the video, my short summary of the explanation would be "centrifugal pendulum in rotating frame of reference"
@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?
it was really simple to me /:
@@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.
Oh my you already got a list you are working on thanks for sharing your knowledge and a bit of fun
that was intense ! it's been more than a year probably when I watched the video by the first time and I did not understand much. I'm glad that today I understand more. Thank yo so much for what you do. You are awesome !
The goal of this video is to prove Feynman wrong. *8 minutes left.*
Lol, i did the same thing! When i heard that i paused the video to check the time remaining. :D
Well I don't think he succeeded, it's not very intuitive at all
Ow ma god ur incredible
This is a concept that's somewhat difficult to comprehend intuitively ... like Euler's Identity.
@@_BangDroid_ Isn't it? Like, it's basic stuff tho. Average high schooler should get it without any problem...
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.
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 😂
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)
@@andyclark4627 it is sphere-ish. But it is heavier in areas like the gravity image of Mars he showed
Watch his other videos. He has some seriously cool plot twists involving nothing but science
Isn't this just a special case of the butterfly effect?
Thank you. I wondered why the intermediate axial theorem didn't appear to apply to the planet. Thank you for clearing this up.
Well done, first time I have seen someone go through the trouble of showing a rotating frame of reference. How a rotating body sees the world around it and the centrifugal forces it experience.
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?
maybe thats why the earth flips its poles.
That's a neat plan. Unfortunately, you'd have to fight against gravity.
Please note that "bunch of mass" also includes the Moon.
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.
Most likely
I’m just happy there is a scientific explanation for that
Sve je to ok ali sta je sa derbijem? 😜
@@Protonneutronelectron Croatian?
@@Protonneutronelectron kako to misliš reći?
Even if there wasn’t, there would still be an explanation, it would just be a unknown explanation.
Trump supporters be like, it changes direction because god told it to. Case closed, no more discussion, solved.
This is the best explanation, thanks Derek
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
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.
enter flywheel effect
Proving Feynman wrong is one hell of a task... yet he kinda did it ... :D
technically Terry Tao was the one who proved Feynman wrong, Derek just reported on it :P
@@MirorR3fl3ction ... well credits to him then :D
He just plain did it. Took me a while to accept that as fact.
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.
@@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.
I noticed this 7 years ago or more when I was into butterfly knives , actually I'm not sure if it's related , but if u try to spin the butterfly knife so that the narrow part of the knife rotates it will try to open . When you spin it length wise so that longer bit is moving it will force the knife to open after a few rotations if u manage to spin it fast enough it might do it a few times too
Thank you!!! Ive been wondering about this for so long
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.
Interesting point! Kickflips and shuv-its are common tricks, yet the impossible is well....harder to do!
@@bradleyries2817 the impossible is my favorite trick and i think tony hawk did a video about this physics property
I’m kind of surprised there aren’t more pro skaters who like physics, it makes logical sense haha
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)
Hmm u r R8 actually feyman thought on this only for 15 second thats not fair.
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.
Also me haha !! - noticed the flip since school days with my ruler and since then always tried with rectangle shaped things
Flipping TV remotes is incredibly entertaining
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.
I loved learning from this video. Thank you so much!
Really good video!! Thanks, well explained!
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. 🖖
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.
@@kurtreber9813 Ditto. I'm high IQ, ADD as f$%k and embarrassed to admit I didn't question a single thing.
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
@@wonderingalbatros3603 I'm only 95th percentile ... a bit thick really 😜
Ya know, some read books and others realize physical phenomena as the books fly through the air.
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!
You're never to old to learn, you can teach an old dog new tricks. A wise man once said.......
@@markgomez3688 TOO, with TWO O's, TO be exact.
@@samfreed7251 So what!... It's not like i am writing a letter to the Queen... oops Queens speech is on now , must go....
Basically fulcrum crowbar on invisible fulcrum crowbar.
🤣
Thanks for the simple explanation.
Very interesting and a great explanation! Thanks!
People: They hid it for 10 years! Russian: Chill down I just forgot about it.
Anime Universe: Tusk Act 4!
"chill down"
why the hell did my mind read the second line in russian accent
@@slaughterround643 sounds Russian
@BlazarBlue Use Toilet Paper for Napkin!
I wish this guy was my science teacher back in Elementary School, Jr High School, High school, etc..
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...
Bollibompa that exactly what happened for my grade nine math class. A former nasa astrophysicist taught us about the slopes of lines lol.
I too would have enjoyed him, as my teacher.
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
Kenneth Kline sorry what?
Noticed this years ago while throwing knives. Never understood it. Thanks for the video!
this is why the skateboard trick that spins on the intermediate axis is called the "impossible". You have to keep it stable with your foot.
So technically if we move enough mass from the equator towards the earth poles we can change the rotation axis of the earth?
Yup, though you'll need to move a lot and countering that masses existing RI will exert a toll too.
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
Let’s do it
yay! we can finally fix the true north/magnetic north alignment!
@@Uocjat love the OCD 🤣
The crazy thing is, skateboarders, specifically, Rodney Mullen, intuitively knew this when he developed the "Impossible" skateboard trick back in the 1980s.
The best one. Ever.
No. They attributed it to air resistance.
No.
You also watch Physics girl don't you :)
@@French20cent On occasion. Actually landed on the Mullen - Physics Girl episode on a Tony Hawk youtube bender.
I could follow really good. Thank you!
This video actually helped my tremendously in my physics class on angular momentum and torque lol
Oh..., that’s why the bread always lands butter-side down.
you bread spins when you drop it? wish my bread was that cool
Best clinical experiment: Tape toast, butter-side up to cat and drop them from height.
That's Murphy's law.
That happens because it's heavier on the butter side, that's all.
@@DNVPIVIN It is heavier than none 😉
The tennis racket theorem is so cool. I saw it in my mechanics course years ago and it is still fascinating to me now.
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.
dalton cook there should be a machine that will flip it perfectly just to see if we can do it with it half turning
I think i commented about this one a long while ago, i first noticed the phenomenon while flipping a TV remote just like the tennis racket. Great to get some closure :)
This guy solves my problems, that I never had. He's simply awesome. 😍 I always learn alot from his every video ❤
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!!
Lol
@Carl Glennerster LOL!
Nice fib, bro.
i dont smoke no lope
Lmao
I had advanced dynamics for my masters, and this was the best explanation I have ever heard.
Thank u veritasium, very nicely explained 👌
Even as an experienced mechanical engineer, I am amazed at what I don't know. Thanks for this,
So... if we put huge weights in arctica and antarctica, we could make the earth flip?
No, because it is still liquid inside. It would then start spinning at a 90 angle. So half a flip...
We could use the dead useless weight of all the flat-earthers.
Earth is cube
@@the_original_Bilb_Ono Good answer
Dats illegal
Hi Derek, the notification of your videos makes me throw all my work away and sit with my tab. You're incredible.
Me too
same for me too!!!!!!!!!
One of the best educators on youtube!
+1
😂 I was in the middle of math then I'm like, Me : I shouldn't... My brain : *it's still math only interesting*
Man, these animations are always top notch.
ive known about this effect since i was a kid. I didn't know what it was called, but I would do this with my tv remote. it fascinated me how it was doing a half twist in the air. i started tossing the remote higher so it would spend more time in the air to get the full twist or even 1.5
Man! I've always wondered why this happened when I flip the tv remote like that.
Me too.. I obsessed with spinning things
Yes!!!! Me Too!!!!!!!!
Came to comment that exact thing 😳😳
I always thought I just had some mundane skill.
Wait, so if there is no "bump" then would it not exhibit that effect at all?
Coincidence: Just started to learn about Moment of Inertia in school. This helps man.
TY for the heart.
It's like mass, for rotation. In other words, how easy is it to change the object's rotation
Landau and Lifshithz man.. refer to that book.. that is gold
They're listening
This helps man, this helps animals, this helps rock, this helps universe … Let's eat grandma.
Flipping brilliant!
I see what you did there.
Am I correct - When rotated about intermediate axis ,the body tries to rotate it into maximum MOI axis hence we se Dzhenibekof effect as it's resultant....?
Yay I like much that Vertasium is back at interetsing but not so popular topics.
yes very interenetsing indeed
This explains everything, the Russians have been rotating me a 180 degrees during my sleep.
I don't get it, but I like it.
😂😂
You win.
@@cheem2952 Please Watch this: kzhead.info/sun/e5iue9uuh5ewZps/bejne.html and if you like it, subscribe, click the Thumb up and please share it. Thanks Mick
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?
Thanks this is super interesting. It brings to mind the recent discoveries of the massive blobs of higher density that's been found inside the earth. Its thought that these have higher density than other parts and if you look at some 3d maps you'll see that they support these rotation theories as the blobs are centered along earths 'mid riff' so could possibly be the factor deciding earths orientation.
Like the stability-bar on top of the top rotor of an RC helicopter.
Nice video! You should consider doing a video dedicated to why we have or think we have magnetic pole shifts on the earth
Over 300 people broke their phone after watching this video.
I wasn’t one them but thanks for the laugh 😆
I’ve flipped my phone so many times
Not when you tried it on your bed
Start a WhatsApp warning message then. :D
I broke my washing machine
Mum: “so what did you learn today?” Me: “it’s spinning about its maximum moment of inertia”
Amazing ... great presentation
This reminds me a lot of the Wilberforce Pendulum, in which a bouncing up and down motion shifts to a rotating motion and back again, the KE phasing back and forth between the 2 modes. And there's a swinging mode also I think.
This is literally the back bone of skateboarding flip tricks
Yy
Rodney Mullen was interviewed by dianna of physics girl about the intermediate axis theorem
Well, not "literally". It's not an actual backbone. That would be just weird.
@@ClarkKant1 Yes it is a backbone. its the Backbone of skateboarding, literally. Matt said it is and i believe him.
@@TheB1RDY100 it's someone's spine? That's what the person above you was saying
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?"
The questions asked show just how deeply deluded people are who say they understood the video.
@@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".
no, the question is - how much mass(ice) has to disappear before we flip?
@@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.
@@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.
This is amazing thank you!!
Great explanation! Tks
"Mathematicians, Soviet Secrets and the End of the World" Woah there, slow down buddy.
title for a REN-TV shows
He just got up to speed for the bold move: Proving Feynman wrong.
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...
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
@@benjaminshields9421 (•_¬)
I always thought I intentionally flipped my tennis racket like that.
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.
My condolences!
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”
@@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.
Sol Ascending ik? I just answered the guy
Reminds me of the inertial roll coupling experienced by some aircrafts (F100, F102). This was theorized by Philips in 1948, and experienced some years later..
@Veritasium. This was very enlightening. As an Electrical Engineer, I spend my time understanding the intangible. I’d really love to have a discussion about this topic and the history of Earth and global warming solely focused on the potentials of this science.
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!
@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.
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.
@@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.
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.
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
Ya knew something screwy was going on.
@Veratisium This is a great video. I wanted to ask (for clarification): in your disc rendering of the “intuitive explanation,” it seemed to be a requirement that the two smaller point masses were slightly off of the intermediate axis. If they were not, would this effect not occur?
Is it the case that in reality impossible to be perfectly balanced?
I had seen a video on this subject awhile back and today I heard something about it and it turned on the lightbulb. I searched for a video of this happening and wrote in the comments: "I know why they do this, and it is a lot more simple than it looks!! To figure it out, all you have to do it watch the ending half of this when the handle spins slowly enough that you can play in slow motion and see the moment of change. It is a balance issue from material being removed to add in a set screw location for the handle. That small imbalance is enough to cause the flip every few rotations due to build up of imbalance. The handle part of the T handle doesn't play a role in inducing the "dancing" effect." Then realized it wasn't even a science channel and wanted to put this somewhere that others would read it instead of readers just being awe struck with the video alone and ignoring the how and what is going on.