Lec 14 | 8.01 Physics I: Classical Mechanics, Fall 1999

[Mentord]

Did MOMENTUM make that ball's light blink ?

[Bendvlblue]

teaching physics, LIKE A BOSS!

[thomstou]

Oh COME ON people, laugh! 14:05

[usabbott48g]

Your vid is popular on Kenya

[chris12321222]

who cares, nobody is going to fly away from the Earth and fly far away for years at a constant speed

[GamerShaddow]

i didnt understand a word. :)

[oingofan]

Why did this pop up while searching for long island iced tea recipes? Then again, he did start the lecture about "escaping the earth"...

[sk8ingonfire]

free energy would be nice

[x2thezful]

so this helps me get a job how ????

[IndigentiaSumEgo]

Lol, I love how they all pick on the fat kid.

[Mavo1122]

blah blah blah lol

[RAG3D397]

Thumbs up if you're here because you searched " 98 percent of people can't watch this video for more than 15 seconds " .

[miroslavtzenov]

I love physics but I hate math... :(

[Elzelgator]

PLEASE SOMEONE HELP...

1)Can object with a constant acceleration reverse its direction of travel??

2)can it reverse it twice?

PLEASE I NEED ANSWER TODAY....

ıf any one see this comment help me....

[Dave67004]

@Elzelgator I suppose you could have an object undergoing uniform circular motion. Then its acceleration is constant (centripetal, v^2/r). At any one point on the path, the object would be moving in a particular direction (tangential to the circle). After it has completed half a revolution, it is going in the opposite direction. Once it has completed a full revolution, getting back to its initial position, it is going in the original direction again. Constant acceleration, 2 direction reversals.

[Dave67004]

@Elzelgator Further to my previous post, I guess this only works if you just require the MAGNITUDE of the acceleration to remain constant. Obviously the DIRECTION of the centripetal acceleration is constantly changing as the object moves on the circular path. If you require both magnitude and direction to remain constant, I don't see how it's possible! Hope this helps :)

[Elzelgator]

@Dave67004 i think you are right. i am not sure but its sound, posible.

centripetal acceleration will be constant and also direction will change.

thank you for your help. 

[CorruptionData]

I don't even know long division. lmao

[chomakk]

Doesn't the ball have 2 watch batteries in them to make them flash after it's triggered by an internal switch?

[dmessi19]

@chomakk Yah I think the Energy is chemical energy from a battery somewhere in the ball not from gravitational potential energy !!

[b3stbuddy]

What?

[rungun12345]

โหดมากหัวขาว

[PJRehlaender]

15:50 what a dodgy bicycle. If it came like that from the shop i would take it back.

[ivaneduardo747]

@PJRehlaender Does it really matter? As long as people understand the class it is going to be fine.

[Tobra1]

I remember this day.

[tomsanzf]

If the period of the earth is 365.5 days shouldnt leap year be every 2 years and not 4?

[ilostmyfiles]

@tomsanzf you're right but the orbit of earth isn't circular either so that being inexact is probably good.

[IndigentiaSumEgo]

@tomsanzf

It's an approximation he made from empirical data. Bound to have some error.

[guitarman4871]

14:20 hahaha.. awesome

[junior1984able]

mechanical energy= potential kinetic enrgy

[junior1984able]

mechanical energy= kinetic energy

[SuperHantamsajalah]

make me headache...

[Voudim]

WOAH THIS GUY IS AMAZING, I WISH YOU WERE MY UNCLE AND COULD TEACH ME MATH

[kruger4444]

John Malcovich?! O_o

[Cifrocco]

In every Youtube video there's always someone that asks how he draws dotted lines with the chalk, lol. How do you think? Maybe it's an electric chalk with a little battery-powered solenoid in it, lol. Or maybe he's a very nervous guy and when he doesn't make an effort to control his hand it vibrates, lol. Of course the real answer is that he's holding the chalk at an angle that is greater than 90 degrees relative to the direction he's writing in. Doing so causes the chalk to jam and skip.

[Nick153452]

This guy has ADD

[maninheaven1]

wow.

[h0wud0in2]

ahahaahah you can do no work in a lot of time and you have a lot of power. calculus in politics

[takekideasy]

I found no reasons to dislike this vid:'(

[Stratocaster1111]

"Much nicer to have a human being with you in bed than one electric blanket, believe me."

-Walter Lewin

[sequentialproduction]

too easy

[mousavi128]

How does his chalk draw the doted lines? I'm really curious about it...

[mousavi128]

How does his chalk draw the doted lines?



[kshinya007]

@mousavi128 I thought everyone learned this trick in grade school?

[mridularul1]

the brainteaser's answer which was asked at last is that there's a coil or a type of solenoid inside the ball and there's a permanent magnet in side the coil suspended by springs which starts oscillating after the ball bounces and due to the change in the magnetic field current is produced due to which the light blinks and keeps on blinking until the permanent magnet inside keeps on oscillating.Quite Easy :)

[mridularul1]

VVVVVVVVVVeeeeeeeeeeerrrrrrrrr­rryyyyyyyyyyy Interesting!!!!!!!

[extremelyfatass]

This guy is stoop.

[otTbc123]

so confusing....

[FelipeZucchetti]

nice video...thanks for the class...

[JonThm]

You should be investigating molecular nuclear fusion

[reboothater]

ever notice that educational videos have video responses turned off. its because educationalists dont like anyone arguing with them or thinking for themselves :) lol.

[reboothater]

the decimal system is also bjorked as division is incorrectly taught. :p ehe. secondly thier is gas in space, stars give it off. stop saying space is a vacumme. its not, its filled with both starlight and radiowaves from stars.

[reboothater]

if you ever see someone using algebra that isnt using it for basic math its a sign they have no clue what thier doing. :) and unfortunately that pertains to even nobel prize winners. a proof is a quick way of explaining something rather than give 5000 examples, all agebra codes are suppose to be proofs for doing basic math calculations (+,-, x or / ) :p

[reboothater]

for example instead of me writing 5,000 proofs of in order to find the number of seconds in a given number of minutes, i simply use a formula and DESIGNATE what the initials are for. 60 x m = nsm m is = any whole number given number of minutes. nms=number of seconds in a minute. if you multiply 60 by any given number of minutes you get the number of seconds in a minute. thats clear algebra code writing.:).60x2=120 (120 seconds in 2 minutes).algebra is suppose to be used for doing basic math

[reboothater]

@reboothater sry nsm=number seconds in a minute not nms.

[reboothater]

if the earth is moving constantly around the sun (which is why we have time itself) that means were traveling with it and momentum is continuous. i hope the teacher is aware as it looks murkily suspicious, that be sure an explain that a algebra code isnt simply ab+cd+f. algebra codes are suppose to be proofs, a way of initialing a basic math problem. i see alot of murkey algebra done without stating what symbols mean what.

[reboothater]

also your guys's idea of rest is rediculous. the reason rest does not occure is the earth constantly rotates and traveles around the sun. if rest occured, time would be able to stop and things wouldnt age. all things age and decay, even if they are sitting on the ground "resting".

[reboothater]

the problem with using math to determine energy outputs is that energy outputs are not fixed and static. if they were fixed and static objects that generate energy would continuously generate energy, we wouldnt have power genereative problems in electronics for instance.. secondly infinity is not a fixed amount it means forever or to increase continuosly.

[1888junkteam]

excellent work!

[GPrankG]

he is incorrect, the circumference with a radius over 1/2 PieMmG using Berkley theory is the kinetic force of gravity in orbitational form causing it to be 8*95 to the power of 8

[lilhomieeee]

30:54

it will power your electric two-shhh-brush

[Himali645nepali]

if you are from this world and if you are human being watching this vedio. I hope you are not commenting in bad way, try to value the type of education he is giving. For those people who are talking about metric system. That is good idea, but we are in America. This is our uniqueness ,that we have this system. And if you are American, be proud of what you are. If you are not proud to what you are. You have problem. And if you are not American; I tell you one thing, MIT if no. 1.

[oramato]

IN THE US: The use of the metric system made legal in the United States by the Metric Act of 1866 (Public Law 39-183). This law made it unlawful to refuse to trade or deal in metric quantities.

1893 Mendenhall Order: metric prototypes were declared "fundamental standards of length and mass" in the Mendenhall Order. Since that date, the yard, pound, etc. have been officially defined in terms of the metric system. Conclusion: You can lead a horse to water, but you can't make it drink.

[asinwt]

Great way to describe to the Power one puts riding a bicycle, starting at 15:00 !

[Shilpa2601]

fuck i needed the video not this

[coolguy6075]

I think that not a lot of people use the opportunity to watch these vids

[komm1981]

this alien system in us, us shuld switch to metric. whic is universal system.

[Voudim]

@komm1981 no because America is the greatest country on earth.

[willc403]

what's the answer to the brain teaser ???

[xlDylanx]

this guys mad smart, makes me scared that ill be taking this some day :\

[rookiegamer]

what's the answer to his brain teaser in the end? o.O?

[JdaviesJ]

I'm listening to this guy, thinking, "Boy, does he have a Dutch accent...!" His name threw me off --it's not particularly Dutch-- but, reading his background info, apparently he worked a lot with Dutch people. Is he Dutch after all, or did he spend (too? :-) much time here?

[JdaviesJ]

Never mind, Wikipedia says he's indeed Dutch.

[trisky1234]

Guess I wasn't the only one wondering :)

[hazemfahmy]

He's not wearing any weird item in his right pocket this time

[gandalfpres]

He does have a rather strange looking bracelet.

[juanm429]

If you think the bracelet is strange, you should see some of the other videos where he has a banana on his shirt. I think it's a pocket protector.

[djibril1000]

the units this guy uses are strange

[LiquidOX2H2]

@djibril1000 it's the international system bro, get used to it; everybody already has ;)

[funnyasdeath]

........

[Eigenerror]

maybe magnets attached to springs on the inside so each time the magnet oscillates past a looped wire, it creates a current?

[happymcjagger]

@ 1:06, shouldn't it be R^2 and not R :S

[Drifter01]

I knew that already....;-)

[ItBeEmmyy]

i want that chalk.

[demon824]

writes smooth.

[MagellansUnderwear]

Glad I found this, this is awesome stuff

[X3QT0R]

Whats the answer to the last question

The blinking may be due to some oscillation.

But i dunno what kind of balls are those.

are those one material.. or something they built.

How abt piezoelectric.?

damn these are seriously brainteasers "P

[Wuzzi55]

stopted the video during 9:47, but as far as physics goes, he taught as much as we learn in grade 12 physics in like 1 - 2 lessons. Imagine sitting there now an hour every day...

I didn't say it is hard though, but excessive

[tracstar9876]

Wouldn't like his tests... What level of math is this???

[blackspoty2]

easy - are you stupid?

[tracstar9876]

sure, why not?

[freeyourmindusa]

how much can i learn from this i need a good job lol. for real.

[nikotina2003]

OMG horses per hour... xD I meant horse power ,sorry...

[dggfhdfghdf]

no,... its a real term, "horses per hour"

j/k LOL

[nikotina2003]

really? what does it measure? :P

[nikotina2003]

I don't quite like how he mixes units... sometimes he's using the ISU, and sometimes he speaks with inches, miles, feet, horses per hour... though he's still a great teacher

[WarzSchoolchild]

I suspect 'nikotina2003' that Walter Lewin is using these units within a historical framework. He names the scientists after whom the units are made. ie. The 'joule' after James Prescott Joule, The Watt etc. Who knows, they might name a unit after you? if you discovered a new and important measurement.

[nikotina2003]

yeah, how I hope becoming important enough to have a unit named after me, hehe...

but what I mean is that Walter sometimes uses the metrical system (the official one in the International System of Units), and sometimes he makes use of the inches, feet, yards, and so on. I guess that he does that just to make his students understand better, since in USA they use them in everyday life (I think).

[ofey137]

whats the answer to the question at the end?

[matteolegna]

I think the balls contains some batteries that provide the energy and the lights are turned on by an accelerometer that that detects the impact with the ground.