Why Do Things Spin? - with Hugh Hunt
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- Опубликовано: 22 май 2024
- Why does a spinning top stand up? Why doesn't a rolling wheel fall over? And how does a falling cat always manage to land on its feet?
You can find more of Hugh's work on his website here: www2.eng.cam.ac.uk/~hemh1/
From topspin in tennis, to angular momentum in ballet dancers, to satellites in space, spinning things are strange.
Hugh Hunt explores the common underlying threads that link all of these interesting phenomena, using examples ranging all the way from boomerangs to cats in this talk for our family programme.
Hugh Hunt is a Reader in Engineering Dynamics and Vibration at Cambridge University. His research centres on the control of noise and vibration from underground railways. He is now promoting other technologies for the removal of non-CO2 greenhouse gases and also runs the Cambridge Climate Lecture Series which aims to raise awareness of the urgency around climate change.
This talk was filmed in the Ri on 7 February 2020.
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Tennis, ballet dancing, ice skaters, satellites, boomerangs, gyroscopes and - of course - CATS! There's just so many spinning things explained in this video that we can now count our head as one of them, too. As always, let us know what you thought about this demonstration-stuffed talk here in the comments!
Can you explain where the force that makes an object spin came from ? It's the rope ofc, but then it would have been nice to dig a little (like, it's the solidity of the rope and therefore some atomic forces are at play) and not just make it spin without real explanations. How comes the constant acceleration that deviates the ball is not consuming any energy since an object going in circles is constantly changing its own direction ?
@38:00 When Eric Laithwaite tried that experiment, it was not exactly the same. He put a plank in equilibrium over the edge of a desk, held by a weight. Once he put the gyroscope (which was spinning much faster than that bike wheel btw), he could remove the weight and the plank would not fall. THAT would have been interesting to explain instead of using just a dynamometer.
Next time Hugh is in town we'll find out for you! Sadly we're not particularly good spin doctors ourselves.
@@TheRoyalInstitution
Heh, "Spin doctors" :) . Thanks in advance if you ask him.
@@TheRoyalInstitution im sure you will find out soon enough now
ill be waiting for the video :)
Conservation of angular momentum doesn't exist. For rotations to exist either the space between all cosmic objects must be completely empty, or all cosmic objects must have their own self-propolsion system.
Completely empty space doesn't make sense and makes the propagation of Gravity and Light impossible along with question why do all Planets rotate around the sun in one plane. By introducing Aether these problems are solved immediately.
There is a book right now on sale on Amazon discussing just that. Title - Blunders of Science and Religions.
In this book there are answered not only these questions, but also what is the true pattern of Magnetic field. Yes, our textbooks have it wrong and the book proves what and why is wrong and what is correct in this respect.
Also, the book answers the question of Leibnitz that seemed to be unanswerable by far - why there is anything rather than nothing...
Existence of aether can be proved and the book suggests an experiment for that. It claims that vacuum doesn't exist and is impossible.
Also, things like black holes, Dark Matter and Dark Energy are answered there.
Among other things book addresses question about free will and what is Truth, how flat Earth is absolutely impossible but hollow earth is more than possible according to experimental evidence.
Tides? Yes, the Moon causes them, but in a completely different way than science explains it.
So, happy reading.
Made for children. However, as a 60 yr old, with an electrical engineering background, these lectures entertain and educate me. Thank you.
We're so glad you enjoyed it, Gary!
Gary, I was about to make a similar comment. I was going to give it a brief look when I saw the target audience, then I thoroughly enjoyed the entire talk / demonstration. I'm 72 (how the hell did that happen?)
"Made for children." but not just for children. A tradition nearly 200 years old has to be for everyone.
I agree with you but I'm only 50, and a welder, not an engineer. Frankly I think you guys need to think about how hard it is to build the stuff you design.
Of course you are the wrong sort of engineer to complain to, but in case you know some structural engineers...
I'd say made for layfolk, dear sir. They've been at it for a while now.
@@MrAaronvee Shut up you bellend.
I know these are all meant for kids up to about 16, but I'm twice that and get excites every time I see a new upload. Such great presenters explaining complex things simply.
Its a great example of "if you can't explain it simply, you simply don't understand it".
that's my motto!
I love these lectures :D.
Thank you Royal Institution for making them available for all of us to watch around the world.
He's REALLY good with children - supportive, sensitive, responsive, and clear!! An ideal teacher.
thanks. But it works both ways - kids are an insiration too.
He is, it comes from both being a university lecturer and a scout leader (which is where I'm sure he gets his absolutely fantastic way with kids)
The experiment with the water bottle, the piece of pipe, the length of rope and the Revolving tennis ball (@10:36) is the best explanation and demonstration of Angular Momentum I've ever seen.
The Royal Institution is a national treasure!!! It serves educational purposes that no single school or university can easily duplicate, and inspires minds young and old, to become more interested in and to engage in the scientific process on a national and international level. May it last as long as our civilization and beyond!!
23:01
That little affirmation from the crowd, had me laughing for about 5mins.
I wish that kid all the Joy's of life, in return !
I love the RI lectures. Even as a 30 year old they take me back to the feeling of being in class with one of my favorite teachers growing up, of which there was only a few. I really wish more places did things like this, especially for my future children. Unfortunately there isn’t a place around me that does anything like this which is quite sad because they’re not just great lectures that are fun for kids and adults alike, they actually teach you real science, and how to think scientifically. It’s great stuff!
That was one of the most entertaining RI lectures for sure. Thank you.
glad you enjoyed it!
It's wonderful to see young children attending these science lectures/demonstrations. Well done RI, well done!
yes, very important - thanks Ri !
This lecture was brushing up what I already knew. However good for kids👶.
Professor Hunt is amazing. So engaging and so much passion for presenting. From a 42yo engineer from the US, I envy all those children in that audience!!! I would have paid to be there!!! Had a smile on my face the entire time. Wide-eyed laughter and ooh's and ahh's are telltale signs. There are future engineers, scientist, chemists and physicists in that audience!!!
that's the whole idea! Glad you enoyed.
@@spinfun if this is really Professor Hunt, I did indeed! Thank you and stay safe. 🙏🙏🙏
That was the most edjutaining lecture I've ever seen!
I remember seeing my first RI Christmas lecture around 1975 on black and white TV
That was also about centrifugal/centripetal force when there was only a single scientist worldwide studying the 'gyroscope phenomena' and a lot less known about it.
Edited, Didn't watch bit where he mentioned Eric Laithwaite, 1976 until later
Loved the talk and children's participation Hugh, excellent... exemplifies one of the many very good reasons we need to organise our climate crisis response urgently. Thanks again.
You're having too much fun and we are learning so much. Great job.
Excellent demonstration.
Just think how many of those kids will be changed forever by this lecture, pursuing careers in science because of it
Maybe they will build a giant bomb and we'll all die.
I wish I had this guy for a physics teacher!!
extremely entertaining and edifying at the same time
lovely lecture-thankyou.
What a great lesson , thank you :)
Ah, today, spinning things and things moving around in circles became fun for me once again! Many years ago, I had been badly scarred in college, struggling with moment of inertia tensors, Euler angles, quaternions and what not. However, having graduated, I feel I've earned the right to gripe about a couple of things in the video (with profuse apologies to Hugh Hunt-your lecture remains wonderfully interesting and educational!).
16:14-When Zoë puts her arms out holding the weights, they feel heavier than when she holds her arms in. That's simply because the weights exert a greater _torque_ on her shoulders when her arms are outstretched. It's not because of the change in her "angular mass", which the slide says at 16:42.
26:33-Hugh demonstrates the _Intermediate Axis Theorem_ aka _Dzhanibekov effect._ I think, however, the children in the audience are too young to appreciate its significance.
Glad you enjoyed! As to your points, I could call in "Moment of Inertia" which increases when Zoë puts her arms out. But for kids I prefer the term "angular mass". All of the gyroscopic stuff is too advanced for the kids, but that doesn't make the experiements worth doing - promotes inquisitiveness ...
@@spinfun Honored and humbled to hear directly from you Professor! I completely agree with you that if you unnecessarily complicate things for children (or anyone, for that matter), they'll lose interest. My point wasn't about terminology. I was saying that even if you're not rotating, holding a weight with arms outstretched is more stressful than holding it close to your chest ... never mind, not important. Again, great video, and I wish videos like this were accessible to me before I was put off by chalk-wielding jargon-spouting professors!
@@nHans Hi, I'm no scientist, I've only read The Urantia Book, but I think if Hugh had of used tools or machinery for his demonstrations it would have been based more on calculations, taking away the human factor you refer to, but it probably would have required a lot more explanation, and been less interesting, less fun and harder to understand for the children, which as he pointed out was his main goal.
I've suggested some models of creation I'd like to see him experimentily demonstrate with or without the human factor, in terms the gravitational effects of gyroscopic energy, force and spin. I don't think it's possible myself would probably require some type of vacume, but hey the Americans nuked two cities in Japan and are still getting away with it, so anything is possible on this rebellious corrupt planet.
Read The Urantia Book bro, all the facts in the world can't explain truth...
I like the angular momentum description and demo, fun
Just great lecture.
Great video. May the force be with you. always, 09:54
This is intertaining and educational for all ages.
Reminds me a little about Walter Lewin's lectures but without the background math.
Both very enjoyable.
He does the same lecture with the background maths too. Mainly to Cambridge engineering undergrads
@@dasy2k1 I found another of his lectures (with a little more math) so thanks for the tip.
I really love that this channel has everything. Like, sometimes I want to watch some stuff about really in-depth things, like the Krebs cycle as it relates to the generation of energy by mitochondria in nerve cells in the brain and how that relates to the experience of consciousness, but sometimes I just want to watch some fundamental also equally fascinating stuff about just how objects move around you know?
You guys do such a good job making every level of science fascinating and wonderful!
This comment warmed our scientific hearts😀! Thank you for watching
Amazing information. Thank You Hugh.
lovely stuff
Delightful, Thank you
Nice to have a explanation about the spin
It has always puzzled me how planetary systems stay together, but add spinning forces to the problem and it all changes. No doubt I should have read more books. Most informative and well presented, I have recommended it for my grandchildren.
Brilliant. Thank you.
Excellent lecture
I 1st learned about gyroscopic precession back when I was in the army as a crew chief on an old UH-1H it’s how we explained how the stationary controls moved thru the swashplate an effected the rotor disc
Love the way he teaches
amazing content
These lectures are easy to understand for general learning. You do not need a university degree to understand the lectures.
Always great,from RI
Beautiful demonstrations!
Little message to the filming and production crew from a colleague: could've helped if camera was better trained on the (preferrably recorded) run-through. Maybe filming close-ups without audience. Also nothing wrong with correcting the talent and asking him to change the position or even act - you're visual professionals so you know what looks and works better for the audience, either live or at home. Some demos were very hard to see or understand what you supposed to look at. I don't suppose you do live switching so it's more headache for the editor of course... Anyways, this one was tough, so thanks for the hard work!
Bernoulli's equation identifies the difference in pressure on each side of a wing surface. Not deflecting direction of air
It’s both, actually
It's centripetal force when you're looking at it from an inertial frame, as an outsider.
When you're the one rotating, in a non-inertial frame, you also have centrifugal force - a fictive force that arises as a result of the interaction between the object and the frame of reference.
Awesome video
So entertaining & informative:-)
So thoroughly enjoyable! :)
Brilliant!
As a person whom studied Physics, its interesting how the person here explains it in a very common-language to the people.
Thank you for that very interesting lecture. I have one comment on your discussion of how wings work. I have always understood that an air dynamic wing works because of the shape of the wing causes the air particles to travel further and thereby faster over the top of the wing which reduces the pressure on the upper surface of the wing thus creating the lift upward.
What an absolute mad lad. He taught me as an undergrad 😁
Every Couple has its Moment in a Field
23:10... 'Clockwise'... That kid's a Genius... It's sounds funny... Like a smart clock
The gentleman in the video with the cat is NASA Astronaut Owen Garriott.
Very cool educational material for my son, but we both came up with the same question. At about the 43 minute mark, when the speaker was on the upper tier throwing the boomerang, would the rang still return to him if he threw it in a downward direction/inclination? common sense says yes, but I can see it being harder for the rang to climb back up after being thrown down.
it does, but only for small angles downwards. In fact a "normal" throw is slightly upwards because gravity is always pushing down.
Awesome!
I enjoyed watching this. I would suggest installing a long handle (axle) for the bicycle wheel so kids can hold onto it better.
Good lecture. But the comment about Eric Laithwaite's lecture was a little unfair. Laithwaite's sin was to posit conundrums where angular motion is hidden from the observer.
Robert Deverell I agree his ideas were developed by others and left once GREAT BRITAIN behind. He lived in Atherton Manchester Lancashire England next town to me.
soo frigging interesting!
I didn't have teacher like him,today i still don't know maths,physics but love to learn thank you Royal Institute.
Nice presentation; nicely orchestrated. Makes me think about the spinning globe and the forces acting differently across the surface, BUT feeling 1G everywhere... bit more difficult to orchestrate that?
A gyroscope might help :)
Indigenous people from Australia were the first people to invent the air foil or the wing of a plane ✈️ a very long time ago which in my mind was an amazing feat all things considered
24:40 is it the force exerted to flip it upside down that causes your angular momentum to change as well?
This was fun!
Very good video... but the description of how a wing generates lift is mostly incorrect. While a wing's angle of attack into the air does generate some lift and a lot of induced drag, most of the lift comes from the decreased pressure over the top of the wing caused by the higher velocity of the air having to travel over the curved upper surface. The result being that a wing moving parallel with the air flow still generates a lifting force.
@@MrAaronvee Are these "physicists" you reference on a t.v. comedy program by any chance?
Make a model aircraft that is pulled by a propellor, but where the propellor has no twist or angle of attack, just two Bernoulli profile blades rotating in a plane. That propellor, relying entirely on the bernoulli effect, will provide "lift" along the horizontal axis, ie thrust, but a pathetically small amount. Most of the thrust, whether horizontally (for a propellor) or vertically (for a wing or copter blade) comes from the reactive force arising from displacing air. Sadly, some textbooks may still be wrong.
Given the 10 seconds I have for a "lift" explanation I think it works OK - but it's not perfect, I agree. The audience is school kids with no understanding of pressure, let alone Bernoulli. If you have an alternative 10-second explanation then please tell!
@@spinfun Every authoritative discussion on the subject I've seen says that the Bernoulli effect on a plane wing's lift is negligible compared to the air displacement component. The Bernoulli effect is real, but its contribution to lift is quite small in the overall achievement of flight.
Yes!
Very good for predicting coin tosses if you understand the flip height.
Do you mean the thing with the tennis racket effect? That only works for object with different momemt of inertia about the 3 principal axis. Try searching for intermediate axis theorem.
35:35 wheel that does not fall.
36:22 top that stays sideways.
Maravilhosa a aula
Here is just a thought experiment. The lecturer is on a bathroom scale. He holds the stationary wheel/gyro and the total wight is 200 lbs. Then he holds the spinning wheel/gyro. What would be the total weight?
unchanged.
“Clockwise” 😂 23:01
looking from below him. CCW.
Imagine having season tickets or a lifetime pass to the RI lectures.
Becoming an Ri Member is the next best thing! You get half-price tickets to our Talks and free entry to our Discourses - we'll just leave the link here... www.rigb.org/globals/join-support/become-an-ri-member/join-as-an-ri-member?
The Spin Doctor?
Just go around now.
Brilliant!
Move along please sir, and don't forget to take your moment of inertia.
Presenter: Stand on no leg?
Kid: ~ jumps into the air~
Genius.
Barnes Wallis and the Upkeep bouncing bombs must have been the ultimate example of this lecture.
I remember Professor Eric Laithwaite getting shunned by the scientific community years ago for a Belief that gyroscopes had a relationship to anti gravity, in one respect, the man had gumption for raising the theory and he did so much work on magnetic levitation.
That's because gyroscopes have no relationship to anti gravity
His comments were very carefully phrased and he did uses scales in his experiments and one did show a lower reading. That used two gyros interacting though. I thought at the time the lower reading was due to the wobble , but he did say it required greater investigation. He did NOT claim anti gravity. Try and answer Eric's question at 34 mins in to his lecture. www.rigb.org/christmas-lectures/watch/1974/the-engineer-through-the-looking-glass/the-jabberwock - he says 'appear to'...
Would there be a market for a gyroscope that didn't precess when force is applied to tip the spin axis?
As a science lover I am thoroughly enjoying this but I couldn't help but notice the mother/ daughter asleep in the audience at 36:00!
Why did the third bounce of the ball (at 8:09 in the video) not reverse its direction?
ball now spinning in opposite direction = topspin and ball jumps forward
@@spinfun Erp, that's perfectly intuitive, not sure why that eluded me... thanks!
@@VinceMcInnis The question in my mind was, why is the collision with the top surface sufficient to reverse the spin, but the second collision with the bottom surface is not enough to reverse the spin again. When the ball exits the contraption it continues to have forward spin after having forward spin before the previous collision. What governs whether the collision causes a reversal in spin or not?
why does the ball change its spin only when it hits the top mirror? gravity?
Nicely done!
So.... bouncing the ball 3 times & it comes back...
but what about conservation of MOMENTUM?
All things spin via gravity. Every object as it begins a fall toward a larger object is faced with two forces of gravity based on the radial distance from it point mass center. The primary object has motion and its forces of gravity are lesser along its radial arm and stronger at its line of gravitational impetus between the secondary object. These different gravitational forces although small induce the secondary object to begin a spin along the rules of the right hand thumb
He's not quite right about the way airplanes fly, it's actually the change in air pressure over the wing vs under the wing. The downward movement of the air is a very small portion of the lift.
Not always. Some wings create symmetrical lift. They have laminar flow and their top curve is the same as the bottom. Take the F-104 for example. But the angle of incidence is positive and that allows the total lift to point from the top of the wing upwards.
Only because he has simplified it massively for the audience at hand
I actually I felt this force before and I know this force personally Because ever since I was a little kid I always wanted to fly in spinning was the only way I could actually get close to flying in an open prop airplane where the air could rush against my face spinning was the only thing I could come tonight and now I just do it for meditation but every time I did it the blood rushed from my arms into my fingers I would feel like pulling force on my hands that was centrifugal force
I wish I had teacher like that in school.
Swinging that glass of water 💦 reminded me of swinging the billy tea as a kid I love science experiments
me too! Grew up in Melbourne, many hols swinging billys in East Gipsland
I bet elf and safety wasn't happy with him spinning things around in front of an audience 😂
Thank you, you made me so very happy. I really felt good watching this. You are a true teacher.
W
Seems like we are all upon a spinning planet or within a spinning galaxy, such that the means to get a relative straight motion going a counter spin may be needed, like the normal force.
This week I has been mostly spinning
I do wonder, if he had thrown the boomerang downwards from the gallery, would it have come back up?
I should have tried that! Yes, it does. So long as the downward tilt isn't too great.
@@spinfun Yes, that would've been an awesome demonstration! Either way, thank you for this great talk on probably the most interesting and mind-wrecking topic in classical mechanics! :D
Hugh Hunt, the Science Guy...!!
😂😅🤣😂🤣😅😂
I wish my physics teacher had this much enthusiasm 😄
I read: Why do things spin with Hugh Blunt.. 😅
Whats your website
If you mean us, we're at www.rigb.org/
If you mean Hugh, he's here www2.eng.cam.ac.uk/~hemh1/
Thank you for your reply
the bouncing demo got me so well i thought the little table on top was rigged.
seeing the why, i felt like a kid again....
That was awesome. I'm going to recommend this video to all the flat Earthers I run into on the social media I use. They need all the education they can get. The only problem is they think it's evil magic.
interesting comment...
@@ohasis8331 Of course.
We all need aducation???? Well that's a funny comment for saying that most of us actually do research and are drawn towards history books and the science of old? I know all there is to know about the heliocentric model. What I don't know about is the history that is not provided to us through mainstream media. There are two reason why the don't do this not one. The reason the don't tell you is because they don't want you to follow that path. They want your soul. I do hope you all find him soon for he is close and we will all have to answer to him regardless of our thoughts. If you have sold your sold to the devil then I don't know what lies ahead for you. All I can say is God bless and hope the best for you all who believe this lie.
@@ohasis8331 so do I lol. Love how you judge some one off what they say. The biggest mistake ever made by man........ Get in the bin
@Bob Trenwith lol. You shouldn't be writing things like that tbh. Shows how little you know with one simple comment. I don't have time for atheists of your nature. You will soon see.
I don't think that rotating chair was from the 1950s. I think it was from Eric Laithwaite's Christmas Lectures in 1966.
Why spin has not changes its direction after 3rs bounce.
because ball (with topspin) is moving in the direction that causes topspin to increase. Thry it!
@@spinfun oh yeah, I made a similar previous comment, but now that you point it out, of course. Now I feel dumb :)
While I have seen a lot of spinning things and the effects of their spin, nothing at all comes close to answering WHY DO THINGS SPIN, as is (currrently) the title of this video.
Agreed! The title of my talk (see the video) is "Boomerangs, Bouncing Balls and Other Spining Things" - not sure the Ri title is quite right, but I'm not fussed - very happy that they have put so much effort into helping make a great video.
This guy is my mechanics lecturer at Cambridge University and he is amazing!