Lec 20 | 8.01 Physics I: Classical Mechanics, Fall 1999

[MrBrucebracey]

love the video man

[clairebehun]

some sweet info here

[thejameskan]

really informative and interesting

[Kricardose]

I am very happy to see the vidoe Angular Momentum - Torques - Conservation of Angular Momentum - Spinning Neutron Stars - Stellar Collapse after you give this

[bebeheuy]

I Love The Video It Can Increase My Knowledge Angular Momentum - Torques - Conservation of Angular Momentum - Spinning Neutron Stars - Stellar Collapse

[3llay]

why were the pictures from the slides removed ?

[AllNamesWereOccupied]

The subject I find least interesting is mechanics :/ Every other aspect in physics seems to be so much more fun

[zueshades11]

lovely illustration ... i wish i could draw straight lines like that :P

[johnny45irish]

who needs a degree when you can just watch these, lol.

[MrDanielMaciag]

hes not extremely gifted, he wouldnt be teaching if he was.

[morningstomper123]

@MrDanielMaciag That's a non sequitur.

[Pisceean]

@MrDanielMaciag It takes a lot more than just being gifted to teach. There are many 'gifted' people who can't explain all those amazing things that they do. Gifted people might not necessarily be able to get their point across.

[redetrigan]

That is some really vivid chalk

[varungargg8]

walter lewin is a best professor ever!! thumbs up if u like his demonstrations too!!.........:):)

[mdgreg]

Would you Expect EVERYTHING to Have Rotation?

[mdgreg]

Carousels Not Merry-Go-Rounds?

[sofiamercadof]

I studied literature but this guy is amazing! He has me mesmerized. It so impressive!!

[Tw4tz0r]

Neutrons travel faster than light.

MIND = BLOWN

[Dave67004]

@Tw4tz0r Neutrinos.

[Tw4tz0r]

@Dave67004 fuck you. its neutrons! :P

[Dave67004]

@Tw4tz0r First, there's no need to get abusive, mate. Neutrons are particles found in the nucleus of an atom. They are composed of three quarks, and are a member of the baryon family of particles. The CERN experiments, where faster-than-light travel was observed, were performed with neutrinos. These are entirely different particles; they are not quark-based, and are a member of the lepton family.

[Tw4tz0r]

@Dave67004 Dingus i was being sarcastic, i didnt mean it in an offensive way. hence the emoticon :P

/hugs ?

[Dave67004]

@Tw4tz0r That's cool! :)

[joshmdmd]

@Dave67004 Thats not the correct way to use the word 'first'.. you needed to have a 'second' lodged somewhere in there. Neutrinos still don't travel faster than light. The satellites used to measure the speed of the neutrinos moved in the time period and this was not accounted for in the experiment. This total motion of the satellites accounts for the neutrinos speed to actually be less than the speed of light.

[Dave67004]

@joshmdmd Yes, I probably should have had a "second"!! Interesting about the satellites accounting for the result; to be honest, I thought the most likely outcome would be that a flaw would be found somewhere in the experimental procedure...

[MrVroosh]

really excellent lecture

[Rad631]

I could understand everything about physics from this series of videos, thank you very much.

[thejahoflife]

Can you imagine if the hourglass rings around the supernova are storing the energy released.

[eraserx90]

@Hourglass1117 i think its a special kind of chalk

[Sankhsarkar1]

okay: @ around7.20.. whe he says that it is onl at the point C that the angular momentum remains constant, but isn't the same case with the reference point being at q too.. here the only difference would be 2r (since it is on the circumference) or will there be a difference in the sine of the angle? if so how?

[SheikahZeo]

5:53 Here is the Earth...

'Damn, that is a sweet Earth' you might say

WRONG

[endpointithaca]

LOOK AT THAT FKIN GILET!!!! <@

[endpointithaca]

fess up - this dude is awesome.

[ayakiguchi712]

I learned English from “fet system”

I learned Economics from “mark thoma”

I learned Math from “your teacher”

[ssa09003]

why'd they remove the pictures?

[darbocity]

25:00 is great!

[ErikssonMattsson]

So this is MIT? I thought they had higher standards than this.

[Paulorific]

@ErikssonMattsson Really? What ( considering that it is 12 years old ) is so wrong with this video?

[Hnajib77]

I would actually enjoy college is I had teachers like this

[pacorredor90]

Why would all the gravitational potential energy be released at once, or "in a matter of seconds" as he says? Wouldn't the star collapse somewhat slowly as the pressure within it decreases due to it running out of hydrogen to burn?

Awesome professor though. Seems quite bright! (judging by the crazy hair)

[freethisone]

the pointing vector of the binary sun is given by nasa. look at a nasa patch. has a pointing vector relative to earth. 33.5 degrees free masons..

[Chemistryisthegame]

Ian Shelton is my astro prof nifty enough

[adrenacrumb]

well done.

[richardbekking]

@41:52 it says "The drawing of a neutron star with its associated magnetic field has been removed from this video." Why was the drawing removed from the video?

[DRAWDE8999]

lol wut. I don't understand

[BJ219]

This is badass, I love it. This immediately cleared up any physics questions I had relating to the topic.

[davesslowgt]

The sun will not collapse to a neutron star it will become a white dwarf.

[mridularul1]

Can anyone please tell me how to take out the difference in potential energies of the sun as normal and the sun as a neutron star, I m confused 33:46.

[MrSajikhan]

i love this professor

[thisisfordproject]

i actually understand this now o.O thanks!!!!!!!!!!!!! <3

[kap2z]

@thisisfordproject

Bullshit.

[letbonist]

@kap2z lmao

[Pirate88179]

This fellow is brilliant and a wonderful teacher.

Thanks for this series.

Bill

[royalsnowman]

why would the pressure wants to expand the star? I thought it is the other way round? 28:17

[Hamking1]

You're right, pressure does want to expand the star. The density of the star, and therefore it's gravity, keeps that expanding pressure in check.

[Hamking1]

@royalsnowman The pressure is the "mass" of the gasses in the star, pushing and exploding away from each other. But the density of the star is so great the phenomenon of gravity comes into play and keeps that expanding pressure in check by wanting to collapse back in on itself. If a star's density becomes so great, and it burns out so there is no more expanding pressure you may end up with a black hole.

[gongwongton]

lol he keeps failing with that "c"

[vkpillay]

I was taught by a great maths teacher who can write better.I never heard of angular momentum a difficult cocept while learned. To me th lecturer should not raise his voice too much that divert attention of students.but MIT is a great institution and may be because of professors like him.

[kashifanaz]

he is really a gifted person

[GrBla123]

I wish MIT adds more videos like this. I am old and do not go to school, bit I love to learn.This is the best professor that I ever seen.

[Pirate88179]

@GrBla123

There are about 50 video lectures online if you search for them. All of them great...and free.

Bill

[98032023]

@GrBla123

MIT has many free courses available on their website. check out ocw.mit.edu

[98032023]

@GrBla123

They have many courses available online at ocw.mit.edu. Or justs google MIT and opencourseware and you'll find it.

[arsenelupin123]

@GrBla123

You have no idea how you  made my day with this comment. Thank you.

[koollyf]

@GrBla123 : You might like to look for MIT open courseware. 

[TheBraziliantV]

@GrBla123 I'm a college student(not at MIT) who actually enjoys learning but boy do I hate my workload. Seeing your comment made me realize I am lucky to be in school and that the work is just another way to learn.

[zackeey]

my physics lecturer actually demonstrated the spin thing! (held weights in his hand and got someone to spin him atop a turntable.) cool yos. :)

p.s.: love this guy's handwriting!

[claptonisking]

SCIENCE!

[atomless]

Trying to view this on an iPhone but just get an error message saying that "syndication of this video has been restricted by it's owner.

[Mert9800]

the guy likes the letter "c" I suppose =)

[hacksign000]

why all professor gotta have hair like that lmao

[methur83shalal91hash]

he is so far the best physics instructor i have encountered.

[josesacramento]

I have no words to say how much I love to see the videos of this wonderfull and great teacher..

Thank you Professor, thank you so much..

I am Jose from Portugal.. Thank you

[TowerCraft]

why removing all the pictures...

[dutchkillz]

Lovely. Amazing Thank You. My Physics instructor was horrible.

[jypeys]

Your videos are helpful. thx for posting them.

[44541620]

why dooes mit remove the pictures from the slide show? copyright? damn.

[CrazyScience]

It is very sad to see that some of pictures are removed from such valuable lectures. It ruins the beauty of this lectures. It ruins the feeling about nature of law about copyrights. I hate that. I am not angry, just very sad.

[hifhif123]

@CrazyScience Why are some pictures removed. Why would their be a copyright on things he draws.

[CrazyScience]

Answered in Safary browswer, but message is lost.

[CrazyScience]

Whole course belongs to MIT, and they decide for free publishing on YouTube, including Walter Lewin's drawings. But, in this course, few pictures belongs to other authors which maybe not give them permission for publishing on YouTube. You may find that pictures just by googling.

Not practical pausing this video and googling for such pictures, but we will survive. :-)

[jypeys]

this video is 51 minutes long!

[technologist1953]

A safer way of doing the "ice skater's delight" experiment is to sit in a swivel chair (eg an office chair). That way you won't risk falling over (but you still get dizzy !)

[summerday44]

actualy, when two object attract each other, their toque making ratio on the system is

r1*f sin(x) /r2*f sin(y)

ah ah!

but sign rule says r1 sin (x)=r2 sin(y)

an f and f are equal but oposite in direction dso torque they make on the system are oppposite in direction of rotation equal in magnitude so they acancel each other off....howly mowly world was made by a talented mathematician

[Alacryst]

"Just hold me! Hold me!" lol :D

"Okay you pass the course." lmao xD

These are so good lectures that I've decided to watch these instead of going to school to attend on our lectures.

[adkinsjr]

I cannot wrap my head around the vector nature of rotation. I just don't see how there can be vectors pointing out of or into the board. if i'm swinging a rock on a rope around my head, how could there be anything happening in the up direction.

[summerday44]

hey man thats just an interpretation. You see in a rotation, the only logical direction that doesnt change is the perpendicular to the plane of rotation. If you thought that torqe is in the direction of rotation then its always changing, but out of the paper it has fixed size, it doesnt matter torque nver push any thing up it only roitate something, force is the linear version, torque is the rotational version.

go to hyperphysics ot look at this course notes

[benjamin6673]

The vector defined by angular momentum is important because it is a conserved quantity for an object in situations of no torque. It is a fundamental premise of physics that free space is rotationally invariant and hence for non-interacting objects angular momentum is conserved.

[misunderstood2020]

he is AWESOME!!!

[butterzbread]

Good presentation: voice fluxuation, legible hand writing, clearly defining concepts, "w/ explanations for misprints".

One might wonder what the difficulty of his tests is and what he allows for crib sheets.

He would be on my preference list for instructors, were I still in school.

[Tobi4444]

the students look bored

[allstarsabc]

What's the matter ,I like it

[iugrehc]

Re: Black Holes, Neutron Stars, White Dwars, Space and Time

[gnaixgnem]

Take a pee outside and you'll become a very famous man!

[slurdas]

GOD!!!51 MINUTES!!

i think i'll pass..

[sentriclecub]

LOL that was funny at 25:20, about passing the course.

[mik1984]

Why every other subject of studies seems more interesting than the one I study...

[nznaturopath]

I understand competely. ;-)

[liveguns]

i'm seem to be having a hard time. but hey its FREE.