Lec 3 | MIT 5.60 Thermodynamics & Kinetics, Spring 2008

[HPPcello2]

they move really slow at MIT

[HPPcello2]

@HPPcello2 we covered everything they've gone over 3 lectures in during my first lecture

[Yeant]

Video ends at 9:00 :(



[dawncoming]

I totally understand the prof. Same thing in my school:that we never care to answer questions that we know the answers of...

[waterskippers]

These videos are 100 times better than the book I spent $200 on.

[caperneoignis]

this guys isn't as good as the other one, nice chap, but he is forgetting to repeat the answers as a person who is use to being video taped would.

[kaozbender]

rofl look at all those chalkboards XD

[herojha]

why is he stressing dU= dW(rev) for isochoric process??? Why does he stress REVERSIBILITY???

[herojha]

I think he is too fast!!!!!!

[alpazmar]

I prefere Bawendi`s lectures

[markomiz]

11:00 when he says the work done by the paddle wheel is mgh... wrong, mgh=work done by paddle wheel + kinetic energy of the weight at the bottom of movement.

[DerSchreiFalke]

@markomiz As the weight approaches the lower limit of its movement, it's kinetic energy approaches 0, and its potential energy approaches its maximum. Therefore, in the ideal-model-world of physics, kinetic energy is negligible.

[markomiz]

@DerSchreiFalke the weight speeds up as it goes towards the floor (acceleration), how then, you absolute genius, can the kinetic energy be approaching 0?!

Try balancing the energies of the water and weight before and after.

[markomiz]

@DerSchreiFalke the weight speeds up as it goes towards the floor (acceleration), how then, you absolute genius, can the kinetic energy be approaching 0?!

Try balancing the energies of the water and weight before and after.

[DerSchreiFalke]

@markomiz I'm... sorry? When was a floor mentioned? The diagram and lecturer only specify a lower bound of motion.

However, I'll explain. Because the weight's velocity depends not only on the acceleration due to gravity but the internal pressure on that fluid, it will likely, at some point, decelerate as it moves toward its lower bound. Kinetic energy is 0, when it stops moving--at the lower bound of its motion.

[markomiz]

@DerSchreiFalke the floor point is irrelevant. But if it will make you happy replace "floor" with "centre of gravity of the body pulling the weight down"

For the kinetic energy to reach 0 the resistance to motion by the fluid on the paddle must be greater than the gravitational force on the weight - impossible, think of a simpler case; pushing a box on a floor with set friction - however you push the box on the floor, the frictional force can never exceed the the pushing force. think about it

[DerSchreiFalke]

@markomiz

You are correct. I concede. I misinterpreted the diagram. I assumed the wheel was actually a pressurized turbine, the difference of pressure between which and the external would have contributed to the resistant forces.

[remuscariasonant]

@markomiz Yeah definitely..Then again i don't think he actually ever says that the heat converted is mgh, he just says that the work done in bringing the mass from h to 0 is mgh. He does say work is converted to heat but he doesn't explicitly say mgh is converted, does he? But i agree that the work converted to heat should be mgh-KE of mass at 0

[remuscariasonant]

@markomiz but yeah sloppy and ambiguous..especially when saying dT=w/cp



[kevinthenerd]

The speed of the lecture is almost more appropriate for a review than a first go-around, but maybe I'm just not smart enough. (They don't call it MIT for nothing.) There is a LOT of material to cover in a course like this, and the fundamental concepts are often rushed in an effort to make time for problem solving. I took Thermo 1 and 2 at UCF, and I graduated just over three years ago. I'm using these lectures to brush up on stuff I don't use at work so I can design a homemade Stirling engine.

[jay7764]

this guys voice synced perfect with music.. lol that's why i made a remix of this video.

you will no be informed with a catchy beat.

[peritech21]

The point is that a lecturer should make the subject clear - it is his role to present a series of interconnected points that clearly follow from each other -- when the inevitable error occurs it should not be glossed over - the flow should be stopped, the error pointed out and the the students asked to confirm that they understand. Prof Field failed in this task - perhaps if his blackboard presentation was better laid out, the mistake would not have been such a problem.

[peritech21]

Prof Field was unfair to his students in the latter half of this lecture. His failure to adequately resolve the confusion with qv and dUv was inexcusable.

[SamuelHLampa]

@peritech21 Well, he quite clearly showed a while before, that dUv is is dqv, for constant volume, so if you just remembered that, it should be all clear, I guess.

[circusboy90210]

@peritech21 maybe that was done for this video to prevent anyone from garnering a free educatino??

[blindsk8r490]

fuckers dude. If i could afford to go to MIT, I would yell out if I knew the answer. I yell out the answer at a community college turned university!!

[circusboy90210]

@blindsk8r490 cost is not the biggest barrier, the cost of attendance is about $14k per year last I researched it's getting past the admissions process, they take only the brightest minds.

[sphtut]

MIT forever!

[Squatchmichael]

I do not envy the man that has to teach thermal physics.

Prof. Levin does a great job with the intro. lectures though. This presentation seems to focus too much on the operational aspect of the physics, not on the insight; again, this stuff is non-intuitive, so it is not a criticism of the speaker.

[rahulpaudel]

Didn't enjoy that much...

[mali75851]

Not giving a conceptual lecture, just wrting stuff from his notes, thats what MIT is about.

[EduardoAlbuja]

When you blow on the hand with your mouth opened the air will flow hot, While when you decrease the hole of your lips the air will flow cold, why does this happen?

[TheHolyJumperr]

In the first case, the flow is laminar, you sense a temperature of you lungs, in the second case the flow is turbulent - you feel a temperature of the surroundings. Try the second case blow in sauna and you will get burnt.

[szirmay]

when your lips make a smaller hole the air tends to flow faster and thus cool down, but if you blow air at the same velocity as when your lips are open wide the emp should be the same

[ibrimustafa]

eduardo

when you close your lips you do throttle air the temperature of air converted to pv work so its temperature drops

[TheHolyJumperr]

Better explanation, why work is equal to 0 when gas expands to vacuum is the force to the piston from the gas is equal to 0 because there is no resistance from surroundings.

[roonaldo17]

I realised what he means now; because dW is welldefined for reversible process and dU is a state function, we measure dU by the reversible work!

[roonaldo17]

At 36: 30, the prof mentioned dU=dW=Pdv, nvm the sign convention. But since he was discussing an irreversible adiabatic process, shouldnt the irreversible work be the same as the reversible work? Why would it be 0???

[ibrimustafa]

reversible work and irreversible work cant be same because of friction. the equation of firrst law of thermodynamics is q - w = delta u does not account for friction, ie heat supplied is going to do the work rest is converted to internal energy. so the irreversible work must be less than the amount of reversible work by the magnitude of friction energy. hope i anwer you although late.

[gbnet54]

I really didn't enjoy it. Too many concepts without a real link each other. It is a sequence not a tale

[Marceltcm]

hauhua bom mas ele se confundiu todo com as derivadas parciais...

[divinenuker]

bravo!