Thermodynamics (part 2)

[bigtopbollocks]

Why is it he had to dance around the math problem? I mean just say it straight p1.v1 = K = p2. v2. So to solve for pressure two p1.v1/v2 is (500.50)/20 = (25000)/20= 1250pa all the canceling and redesigning of the equation hides how completly straight forward the equation is. It is multiplication of the initial pressure 500 and volume 50 divided by the new volume 20 givieing the new pressure 1250 pascal!

[Askate]

my high school science department is a joke thank god for these videos

[TheDarkWolf94]

Pascals are N m^{-2} not N m ^{-3} by the way!

[RottenAppleSeeds]

@TheDarkWolf94 it's been established.....repeatedly.

[narcomanel]

He scared me when he coughed o.O

[stephennesbitt2000]

well they would have to be equal since there's no energy change in the system

[misteratoz]

Woh. Thanks for making PV= nRT so intutive! it makes sense now.

[GuruDeutschland]

you ve done a really good job, but you have to right the equation: p*V=E=W and on!!

Not P. Because P means Pascal and p means Pressure.

[shesperfect469]

I just had some peanuts and I should have had some water with it..

[Calc571]

He is very good teacher--

[xStarkiller91]

125. Not 1250

[Oneill9293]

@xStarkiller91 it's 1250.

[thienfoil]

Sun has more energy than ice cube lol. Awesome comparison

[21piecesofBlue]

peanuts ftw

[alyncurtis]

bike pump

[StAndAl0neCompl3x]

My college chemistry professor is pathetic. (It's evident by the fact that literally 30 out of 33 students are failing his class). You are my chemistry teacher from now on. =)

[narcomanel]

@StAndAl0neCompl3x Yeah except that this is a physics video.

[StAndAl0neCompl3x]

@narcomanel Don't be flippant.

[RobSchneeberger]

lol i just had some peanuts i should have had some water with it my throat is very dry.

[Linusknollhouse]

Love your lectures! If I may point just a slight error, pascal is newtons per meter squared. Other than that, I think your lectures are incredibly inspirational.

[geandily]

Why doesnt he divide 500 by 10 and afterwards divide 50 by 2?

[gpetrovichl]

@geandily he couldve done that too. but the result wouldve been the same.

[angiesm89]

@bassman1993

haha i was just about to write the exact same thing!!!

[unstoic5]

Hey.. nice vid..

but Pascals is newton per m^2

yu wrote m^3..

but thanks :)

[SuperMrBentley]

PV=nRT

[demonmoo]

i always wondered what would happen if the particles reacted with dark matter but it will be a mystery for a long time

[H2obones]

um pressure = force/area acting

and he is wrong ,,,,,, not volume

[alagon]

you should make a video on nuclear fusion. This is the next biggest step for the human race.

[EchelonsBST]

raise your sound quality good vid...

[joshuaguevara]

.....wut rly is a constant supposed to be?

O.o?

[Nysonovan]

@joshuaguevara A constant is a term that never changes.. It's something you learn in like grade 10 math lol. I could be wrong, though. I'm not sure if he's talking about something else. But I'm 90% sure I'm correct. :P

[joshuaguevara]

ok,uh,i get 1/k will still be a constant so he calls it k but uh,still considered a constant since its changed?is the constant not a set figure........i feel so stupid

o.o

[janetzki1]

@joshuaguevara No man, look what he was doing at that time. He was trying to get an equation for K.E., so he started taking terms to the other side.

So, he had:

T = k . KE/N

So to get an equation for KE, you multiply both sides by N and divide both sides by k. That's why he had 1/k, because it had been taken to the other side of the equation.

[joshuaguevara]

im not normally......but im so conused for this one

o.o

uh......hopefully ill get a reply to this soon um, at 7:00 he has KE= KxNxT but thats completely different to the equation above written 1/KxNxT isnt it?someone explain plz?

[ZnBangash]

I don't like the new youtube layout lol. Thanks for the vid.

[Cieros]

Great , just great!

[cardhang]

Peanuts x Vocalchords= Koffing

[alpha2490]

I just had some peanuts my throat is very dry. lol.

[catesco]

these video's are very informative thank you...I like your style of teaching :-)

[Kosekans]

Just to having it said: It's 32 F not 32° F.

[MagaCarey]

1 Pa is not N/m^3.

1 Pa is N/m^2.

Try to add an explanation to the video so it's not confusing.

[orangesherbet0]

for sure. force / area

[LachlanJG]

@MagaCarey

he explains it in the first video

[napster180]

barrel has more energy due to its higher heat capacity.

[samGenius4]

yikes sal! ur coughing at the beginning of the vid nearly blow ma ear drums! lol

[PhilnLance]

Pa is not N/m^3

it is N/m^2 !

but thanks for the vid anyway!!!!!!

[madscirat]

Things I learned from Sal: a=v^2/r, t= 2pi sqrt. m/k, KE=mv^2/2, temperature of icecube < temperature of sun

[s2daid]

I don't understand ?

[sistematico17]

at the end of the video, if we increase temperature, and pressure remains constant, wouldn't the volume have to decrease instead of increase for molecules to bounce more often therefore producing more energy?

[cressilia]

No, no change to pressure=no change to volume, your way is impossible

[PhoenixVK]

the volume of the GAS increases thus makin it bounce more against the sides. (volume of box remains constant)

[sroostai]

thanks from germany

[mindlesskid]

I don't know how you could make such a simple calculation such a painful mess to read. Also, you contradict yourself in the second line.

[sukhoi30mk2]

YO! 1 pascal is equal to 1 Newton per square metre ... it's not cube meter.. it's surface area..

[ezcondition]

please cough away from the mic, i gets to LOUD when you don't

[luisfranydler]

Thought the same! LOL

[ctpwns]

shouldnt p2=125pa? i think you forgot to divide the 500 by ten

[cressilia]

No, you don't need to divide 500 by 10.

[elfera89]

it's ok if he wants.. why are u being so riddiculous bout it

[cressilia]

...I'm confused...

[rick7917]

Thank you so much!

[tomfromdelmonte]

''you'll have to excuse me i just had some peanuts...'' hhahaha, these videos r cool,

[Max11551]

There is a small mistake in the beginning of the lecture. You say the unit pascal represents N/m^3, which, as far as I know, should be N/m^2 (force on a surface).

Great lecture though, thanks very much for this series on thermodynamics :)

[khanacademy]

Thanks for catching that. My brain malfunctions a lot and even more often while recording videos :)

[golu4529]

yoo gr8 i agree plz use some more animation tactics ...to understand easily

[darfunkelidas]

@khanacademy If you find the time, add a little balloon comment to the video rectifying the square meters, might help. Cheers for the great videos!

[LeandraH]

@khanacademy =) somehow i have that too when i'm teaching... even with things i really know... could be an interesting topic... brain surgery? =)

[minooo44]

@khanacademy , Thanks for you important lesson. Just question if you don't mind, what do you mean by "K" do you mean that there is no kinetic energy or what ?

[t0myuri]

@minooo44 I haven't watched the video, but it's likely to be K - Kelvin. Same as Celsius but 273.15 degrees more.

[MIRACLESHAPN]

@t0myuri hes using K for constant.