8.01x - Lect 24 - Rolling Motion, Gyroscopes, VERY NON-INTUITIVE

Lectures by Walter Lewin. They will make you ♥ Physics.
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This Lecture is a MUST. Rolling Motion - Gyroscopes - Very Non-intuitive - Great Demos.
Lecture Notes, Torques on Rotating Disks - Gyroscopic Behavior: freepdfhosting.com/c294f9033b.pdf
Assignments Lecture 21, 22, 23 and 24: freepdfhosting.com/2e96daf94f.pdf
Solutions Lecture 21, 22, 23 and 24: freepdfhosting.com/86109d309b.pdf

Science & Technology

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Feb 8, 2015




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Comments 80
DJ Shuffle
DJ Shuffle 10 hours ago
THIS is why I love university lectures on any subject; the lecturers are passionate for their subject, they're experts in their field, and will not hesitate to throw a pen at a disruptive student. I've still got my notebooks full of hand-written notes and diagrams from my studies at uni, I treat them like the golden essence of knowledge they are. I've got plenty of academic books that go more in-depth on various practises, but I still refer back to my notes simply because they contain the significant key points. Lately I needed to learn something I didn't do at uni that's related to my field, and once I got a better understanding I even turned to some fresh pages in these notebooks and made further notes. I need to photocopy them and archive them as a PDF because losing them would be a great loss.
ProneMan OldButYoung
Professor, u lost me at ”Settle down”
Aeronautic Freek
I dont understand why rotating wheel(at 35:55) dont flip down,which force cancel gravity?it is very non intuitive..
Megha Rai
Megha Rai Day ago
I have a question about that last demonstration. When Lewin sir put the weight on one side of the axis of the gyroscope, their was no paired force on the other side so how was torque generated? For example, for the spinning bicycle wheel on the string, the tension in the string and the weight of the wheel formed paired forces to produce torque. Where is the other force for the gyroscope?
SarthorS Day ago
I'm sorry, but this guy would have made me drop physics so fast. It's like he's in a race. Rapid firing concepts, equations and variables. I would have been struggling to just take coherent notes, let alone digest what he is talking about. If you stumble over something, then you are lost and would have a hard time to catch back up. I have never seen a lecturer rush through things so quickly.
Francesco cosentini
Gyroscope is all you need to prove if the earth is spinning. Think about that before you answer!
S Waldron
S Waldron 3 days ago
No numbers no physics.
David Gaudette
David Gaudette 5 days ago
Will you please explain this: ruvid.net/video/video-JRPC7a_AcQo.html
David Gaudette
David Gaudette 5 days ago
The angular momentum of the spinning wheel looks like the right hand rule for electrical current.. Lenz's Law? I wonder how it relates to the jets coming out of black holes..
Leo Liu
Leo Liu 5 days ago
39:09 "None of these is intuitive."
pyrocolada 6 days ago
The only difference intuitively is that the smaller object would make more rotations.... but, something else... if you round down mass doesn't affect speed... but if you could measure finely enough, the heavier object would go marginally faster... right? Otherwise the Earth wouldn't orbit the Sun... right? Or is there something more fundamental at play that I don't yet understand? I feel it's important to validate the intuition of those that did think the heavier object would go faster... but so marginally so as to be unmeasurable, because of the weight difference between the cylinder and the Earth...
pyrocolada 6 days ago
2:29 Surely he means friction is a minimum there? Because how can it grip or get traction without friction?
Alex berlin
Alex berlin 3 days ago
no...If something is sliding it has more friction than an object which isn´t sliding...For example this is why it isn´t good to drift or stuff like that because the wheels are sliding over the ground and they get damaged more than normal driving or slow/fast driving would damage them
331SVTCobra 9 days ago
8:09 the camera looks at the two pretty young ladies, and I'm like "PAN BACK TO THE BOARD!!" ... I've changed since college...
Teacher! miss you so much
Reee Flex
Reee Flex 12 days ago
I mean if an object is spinning it wants to stay on that plane X y or Z as it is moving away from the center of mass in that direction. When this happens its like you extend the object on whatever axis it is turning on while keeping the center of gravity in the same point.. causing it to be super stable due to its center of mass being so far from the outside point of the object... Its why a top doesnt just stand on its own unless you spin it and when you spin it just picture and understand where the momentum is carrying its weight.
Graham 13 days ago
Interesting lecture. The rolling object is in a battle with the force pulling it down against it's own angular momentum resisting the force, which is why hollow objects roll slower - they have more angular momentum for a given mass.
jad hzim
jad hzim 14 days ago
nothing i studied at school has prepared me for life ... this is just for nerds
A Bunch of Grapes
A Bunch of Grapes 12 days ago
this is for the people that produce your car, appliances.... and the device you use to comment this
Saidul Islam
Saidul Islam 14 days ago
David Blackburn
David Blackburn 16 days ago
I'm just surprised after nearly 3 million views there are only 43k likes. Now that is unbelievable and non-intuitive.
Brian Brooking
Brian Brooking 17 days ago
Lecturer has done this problem how many times? I feel he moves too quickly for his students. Going by the blank faces. No pause to interact to show what he is replacing in the formula. I would have hated to have this guy back in the day to be my lecturer. Lectures should be interactive with students asking or challenging. Great explanations but not great lecturing.
Henrique Feio
Henrique Feio 17 days ago
UAU!!! Congratulations for Your Lectures
Feng Xiong
Feng Xiong 18 days ago
lovely teacher and make the class and science vividly demenstrated to students. Only people who truly loves teaching and science can they have such awesome creativity.
Venkat Babu
Venkat Babu 18 days ago
People think everywhere it is Britain. They don't understand tribal education system. You people are lucky to have such Prof.
Victor Manzatto
Victor Manzatto 19 days ago
I wish I had a professor like this guy back in school.
ruxpin76 19 days ago
I did best in honors physics (my only honors course)....but perhaps I'd have kept my interest and not failed out of Engineering if I'd had more profs like this.... instead of having to listen to "formuwars" delivered hastily and with little explanation... I later finished in Architecture, but may go back. If I can find profs like this. Now I'll make like a Gaussian plane and get the flux outta here.
Shoubhik Saha
Shoubhik Saha 19 days ago
Thank you sir i am from India, I was unable to get intrest in rotational mechanics until I got to see your video.. It used to be a tough topic for class 11
Shane Whitbread
Shane Whitbread 20 days ago
Thatsa how you corner a motorcycle..freakin cool !! thank you for the free knowledge ,cheers !
Drew 21 day ago
Ok, now explain why some mountain bikes only have one front fork?
Hesham Eissa
Hesham Eissa 21 day ago
Jason Boche
Jason Boche 21 day ago
At this point it feels very odd seeing a large audience and not one of them has a phone in their hand.
George McAuley
George McAuley 21 day ago
I found everything intuitive. Maybe there's something wrong with me 🤣
Amadeus M
Amadeus M 22 days ago
@23:11 I *twerk backwards, I keep *twerking, I keep *twerking. Who knew angular momentum could be so dirty??
philippe270 22 days ago
very well explain, thanks Walter
Dawda Green
Dawda Green 23 days ago
Oh so you mean that… eeh never mind 😔
Pau Gasolina
Pau Gasolina 23 days ago
low skill i can do better
Luis Colon
Luis Colon 24 days ago
Love this professor, I wish he was my teacher in high school. Love how he takes the number into practice
Ricardo Paiva
Ricardo Paiva 24 days ago
Amazing lecture!! Being able to watch this is a bless!
sheshin shivampeta
sheshin shivampeta 24 days ago
Which book was he refering to at 29:40? Can anyone answer
hasmouda 24 days ago
Fear of the Dark
Fear of the Dark 25 days ago
They observe me pure roll, they disapprove with contempt
P Fulton
P Fulton 25 days ago
I have absolutely no idea what he's talking about! But, gee, I wish I could draw straight lines and circles that good.
ayokay123 25 days ago
Bueller? Bueller?
Ito Rijal
Ito Rijal 25 days ago
The lecturer sounds like the "Great scott!!!" guy in Back to the Future.
Gabriel Jorby
Gabriel Jorby 25 days ago
I was just considering purchasing a gimball for my camera. I now feel it's going to take me some practise to master it.
stmounts 25 days ago
That's what I like to see..not a 'freedom' unit in sight!
mrjleex 25 days ago
I wish I would have had a prof like Dr. L when I was going to school. Typical lectures in physics were done by grad students mostly w/very limited language skills. They made it tough and very uninteresting. This guy is fantastic.
v1asec 25 days ago
No clue about the calculations, I never got that far in physics. The demonstrations are awesome though. Uh, perhaps I could start from lecture 1 if I want to actually learn something about physics.
Lectures by Walter Lewin. They will make you ♥ Physics.
yes start with lecture 1 and take it from there
Luc De Cleir
Luc De Cleir 25 days ago
He: very non intuitive Motor cyclists: ... he's not driving a motorcycle, clearly
David Witt
David Witt 16 days ago
When we're learning to ride a bicycle or even learning to walk we learn to take advantage of, and to account for, precessional effects. The skills we learn are employed without the use of abstract reasoning. The information is stored in the parts of the brain with software that knows how to use that information to activate a skill, but knows nothing about how or why it works.
2Calam 26 days ago
wow dont get your finger stuck in the spokes after the bench grinder spins them up :O What level physics is this?
Xile Efe
Xile Efe 26 days ago
Now I know that I just need to add weight for me to win the downhill competition.
Kishore Tejaswi
Kishore Tejaswi 27 days ago
hmm, why does he torque so much? :p
Billy Casper
Billy Casper 27 days ago
The mischief maker in me wants to see that suitcase put through baggage handling at Heathrow.
Ratus Bagus
Ratus Bagus 27 days ago
Pure Role to a student used to have another meaning. In fact you didn't need to be a student.
GoneBamboo 27 days ago
Thank you
claudioita9 28 days ago
Richard Grant
Richard Grant 28 days ago
A bit odd going to his notes a lot - I didn't used to..........
Kelp Farming
Kelp Farming 28 days ago
The need to have more afro americans in that class. DUmb down the lesson. Its time
Very important chapter explained by experienced teacher .student may be fully understand by take class with this teacher .
Johann Esbe
Johann Esbe 29 days ago
This guy writing on the chalkboard is one of the most relaxing thing I have seen in a while. Like whisking butter around a heated pan, smooth!
fred pg
fred pg 29 days ago
Professor deserved a standing ovation...
Ted R Nelson
Ted R Nelson 29 days ago
I guessed that the two solid cylinders would roll with the same acceleration. But I would never guess that the shape of the cylinder was more decisive than its mass or radius.
Ted R Nelson
Ted R Nelson 29 days ago
@Lectures by Walter Lewin. They will make you ♥ Physics. Very non intuitive. Thank you professor.
Lectures by Walter Lewin. They will make you ♥ Physics.
what matters is the *ratio* of the moment of inertia and the mass. That ratio is *smaller* for a solid cylinder than for a hollow cylinder.
TigerZero aka Allen
The prof math is beyond what I can follow. Equation manipulation. I get to the Bicycle wheel part. Of course, if it is not spinning it will not resist any change of motion. It will tumble to your will. (As kid working on the bike I learned that concept.) It all goes back to the old rule of a mass in motion wants to follow a straight path. You can twerk it, but once you let go. It resumes a straight path..
You lost me at Pure Roll
66gattaca Month ago
I have no idea why this was recommended to me, I cannot explain why I clicked ‘play’, but the reason I watched it all the way through is that it is absolutely fascinating! Such fortunate students being able to enjoy lectures like this - brilliant!
Corey Hughes
Corey Hughes Month ago
At the very beginning(2:11) I think he made an error saying Vq = Vcirc. Vcirc should be 2Vq witth no slipping. The point at the top of the hoop is always traveling 2X the velocity of the center with no slipping. Or am I remembering dynamics wrong?
Lectures by Walter Lewin. They will make you ♥ Physics.
yes, you are mistaken. But don't feel bad; this is not an easy topic.
IAmTheWaterbug Month ago
Why is the class not applauding! I would have given the Professor a standing ovation!!!
Nik Lyons
Nik Lyons Month ago
I wonder how these affects could be simulated for use in camera stabilization
Nik Lyons
Nik Lyons Month ago
I think this tech is the basis behind overunity devices used in advanced civilizations
Nik Lyons
Nik Lyons Month ago
23:40 it gets non intuitive
Zeus Nitin
Zeus Nitin Month ago
The answer is 3.84 m/second squared
Ok, so I decided to watch this video. The first thing I noticed was his Dutch accent and indeed he's Dutch. Cool!
Michel Joseph Cardin
There is something(s) I need to explain to you.
Th During
Th During Month ago
13:22 ... isn't also about the weight that is attracted proportionally according to gravity laws? Meaning, change the full METAL object with a full POLYESTER object, and the hollow METAL object should be the winner. Or?
Bardo Herberg
Bardo Herberg Month ago
Didaktische sehr gut erklärt
rohith pawar
rohith pawar Month ago
a teacher like that u can except 99% attendance in engineering
jkprez Month ago
I am a retired nuclear engineer and I learned a lot watching this video. A few demos like this back in the day would have saved me lots of hurt to my brain.... :-)
Mshojat Month ago
Eh to me that first one _is_ intuitive. At least as long as you know that falling things of different mass have the same acceleration/velocity. If you look at it as just letting two objects fall (which is maybe erroneous, but is intuitive. I mean considering that hollow ones are slower it _is_ erroneous) why would their radius matter? Personally I think the more unintuitive thing is with pendulums, or even the fact that the hollow cylinder would lose to a solid one!
manxman Month ago
turn it slower then it will go the way you want
Arz Dogg
Arz Dogg Month ago
Wish he was my statics lecturer, stress analysis would have been walk-over.My love for physics has been reinvigorated.Great stuff!!
Steve Murch
Steve Murch Month ago
Superb explanation. Physics is fascinating.
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