Thermodynamics (part 3)

[umbragami]

your mouth is waaayyy too close to the mic. I can hear every time your tongue gets too dry and you have to get spit. it sounds disgusting.

[phonesplanet]

very hard...  waaaaaaaaaaaaa

[lorseafisil]

-273°C :) 

[TheDarkWolf94]

Just one correction: absolute zero does not mean "no kinetic energy", it means that the internal energy of the system is at a minimum (not zero).

[misteratoz]

would a black hole where there's a singularity have absolute zero temperatures?

[Coolguyrob2006]

@Theoneandonly5811 Although the existence of god is wholly possible (just not necessary in my eyes), the matter and energy weren't created, they were always there, just in a hot state of incredibly tiny volume, (PV=NRT), (and if you are going to retort with 'how has it always been there?', I would answer 'I don't know' but I would ask 'how has God always been there too and why can he also break the laws of thermodynamics by creating something out of nothing?')

[vishalrao19995]

hgj

[nickrohn93]

@Theoneandonly5811Ignorance is just blistering from your fingers. I can as well create a fictitious deity, claim it has manipulated something not comprehended by civilisation, claim it the only truth (A or B; with no middle ground, a simple-minded approach) and then finally claim once again foundation-less accusations of blasphemy or apostasy who do not subscribe to it. Yes most logical: "If an indoctrinated 5 year old cannot chose between two (of infinity abundant options) it is not true" -nick

[conventbeaks63]

really jumbled up with ur speech...didnt know wat u was sayin

[ajskilton]

But that's my point, there is no true rest mass and so where it appears in the equations makes those equations invalid and therefore they need modifying.

[SuperGAMBLEX]

at 5:26 you said that 1K is not 5times 5K because temperature scales are arbitrarily chosen from middle and not from the begining of ideal temprature scale but if we take it from begining (-273k)(absolute zero) then can i say that something at 546K(273*2) has twice the energy of something at 273K if both of them have same mass

[HobbsO]

@SuperGAMBLEX He said that 5Kelvin has 5 times the amount of energy compared to 1Kelvin because Kelvin is measured from absolute zero (-273C), the point where atoms have no energy. Rather than Celcius which has 274Kelvin at 1Celcius and 373Kelvin at 100Celcius. Therefore it cannot be said that 100Celcius has 100 times the energy of 1Celcius because 373Kelvin is not 100 times 274Kelvin.

[Sanfordkill100]

Watch Absolute Zero-NOVA PBS for info abt Farenheit and C

[veto050]

1000.30

you should have written it like this (1000)(30)

[lumaix]

According to an article Fahrenheit wrote in 1724,[4] he based his scale on two reference points of temperature.[5] The zero point is determined by placing the thermometer in brine: he used a mixture of ice, water, and ammonium chloride, a salt. This is a frigorific mixture which automatically stabilizes its temperature at 0 °F. (A mixture of ice and water also stabilizes, either freezing or melting at 32 °F though Fahrenheit did not use this point in defining his temperature scale).

[SeaWolfe59]

V2. Not V1 on the right side of the equation.

[lumaix]

 The second point, 100 degrees, was the level of the liquid in the thermometer when held in the mouth or under the armpit of his wife — subsequent refinements. Fahrenheit noted that, using this scale, water boils at about 212 degrees.

[SeaWolfe59]

@lumaix

I was taught that the standard proposed in the old days was the "temperature measured in a healthy englishman's armpit". Its a comical standard but I guess ya work with the tools ya got.

[Ramsdellski]

F = (9/5)*C + 32

[EarendilTheBlessed]

summer 2010 here!

[ThelemicLaboratory]

"cubic metre is the SI derived unit of volume. It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes, was the stère. Another alternative name, not widely used any more, is the kilolitre."

2010.05.09 wikipedia

-tits thx

[MilanLouboutin]

1615 Pa??? Howver the equation states that it's 1615 x P

You just ignored P and gave the answer 1615?

Please explain.

[darthlink44]

Dunno if it was said yet or not, but Fahrenheit was based on the freezing point of brine on the low end, and I believe typical human perspiration on the high end.

[vinodgreat]

its not -173 but -273...degree which is the lowest temperature..ie 0 kelvin.....

[kneight01]

at the beginnin new Temp. =V2...right?

[shubhammaurya12]

The creator of this video deserves a Nobel Prize!

[Zed1967]

You say nothing can achieve zero degrees Kelvin (a temperature of absolute zero).

You've obviously never met my ex wife! :)

[schnappy00]

Youtube comments are not a place for scientific debate.

It's for telling Sal abs. zero is -273.15 C not -173 (4:00) ;)

[n1a1s1i1m]

0K is not possible for real. Uncertainty principle implies the position as well as the velocity cannot be defined/measured with absolute and arbitrary precision. So if we say the KE (and hence velocity) is zero, we're pretty certain about it, which would sound, errr, 'scientifically offensive'.

[Raiyous1]

The uncertainty principle says that you cannot measure both the position and momentum(or velocity) at the same time. You can design experiments that measure position or momentum, but not both. The intrinsic uncertainty would be hbar/2

[ajskilton]

According to quamtum theory no two particles can ever be completely at rest, is this true? If so, can it explain why absolute zero cannot be reached anywhere in the universe? Does this also say something about 'rest mass' in relativity, is there a true 'rest'?

[tombuckley91]

E=MC^2

If something is not moving, AT ALL, it has no energy, thus it has no mass, thus it cant exist.

[ajskilton]

photons don't have mass so do they not exist???

[ginuwine19]

but they have energy in wave form

[michalchik]

There is something called "rest mass" most familiar objects have rest mass.

[brydust]

Actually you are right... but your logic is not.

E=MC^2 only relates the conversion (transformation) of mass to energy (or energy to mass).... NOT that if something does not move it does not have mass. In fact, particles cooled with lasers can have their temperature (kinetic energy) reduced to less than 1K, even though the particles have relatively a lot of energy.

[Kneecap22]

No at 0 kelvin it still has motion, it's just the motion is confined to h^3, h being planck's constant. You can't determine a particles momentum or position with certainty. It still has kinetic energy just you can't access it. It is call zero point energy.

[xtensitymusic]

@ajskilton Since Time is Energy, for a particle to be completely at rest it must be at 0 degrees kelvin. If this were the case, the particle would stand absolutely still, and since it would lack energy, time around it(where the temp is 0degree K), would stand still. I'm not really sure what would happen if you literally froze time, or froze yourself in time, as you wouldn't be aware of it. It's very paradoxical but at the same time it makes perfect sense. Quantum Theory is a tricky thing :P

[dalcde]

@ajskilton According to quantum theory, everything has wave-particle duality, which means everything is both a wave and particle. I don't think it is possible to have a wave at rest, or it won't be a wave. I'm not sure if my logic is correct, but that's what I think.

[JayDee98765]

@ajskilton I think quantum theory also suggests that the idea of electrons as particles is still just a theory? They seem to behave like waves as well.

[yellowmetalcyborg]

@ajskilton Theoretically, you cannot reach universal limits, (0K c etc....), but you can extrapolate and get pretty damn close. You can find the true rest mass pretty accurately by extrapolating the data you get from near zero K trials.

[Beelzebuds]

@ajskilton Perhaps it is not a question of where it can exist, but when.

[freydawg56]

So, if i'm sitting here eating my Ramen, watching your video, and my ramen just came out of the microwave, at 120"F and i wait until it cools down to 105"F, then eat it, will my body convert less energy than before ?

so basically does the temp. of eaten food affect the energy obtained from it , assuming you can digest it at that temperature  ?

[Ctesibius956]

@freydawg56 If food is at a higher temperature, it will simply raise your body temperature. As you body temperature rises, your body will employ mechanisms to dissipate the heat. Your body cannot convert thermal differential into usable energy.

[12986553]

"They're not even blinking" (lol)

[StarFury2]

At 0 K (-273.15°C) electrons still rotate around the nucleus, but the atom itself remains stationary and with minimal kinetic energy.

[azngothopz]

@StarFury2

so what ur saying is eventhough the kinectic energy is zero, something with mass is still moving.. interesting

[StarFury2]

No. I didn't said that, at 0 K, kinetic energy of an atom is zero - I said its kinetic energy is *minimal* (lowest possible).

Here's short except from one website text:

"Near absolute zero, electrons continue to whiz around inside atoms. Moreover, even at absolute zero, atoms would not be completely stationary. They would "jiggle about", but would not have enough energy to change state." - says quantum physicist Christopher Foot of the University of Oxford.

[Thymonico]

Aah.. I think he's saying, that even though the atom would have 0 kinetic energy and no movement at all, its position would change continously because of the uncertainty principle. So even though it changes position, it never "travelled" from its original position to the new position in what we normally think of as travelling... Thus, one can jiggle about but still be at 0 K. Oui? :)

[azngothopz]

@StarFury2

lol but wut ur saying is the electrons would still move, but the excerp doesnt say anything about electrons moving, and even if it does, how would they know the atoms wouldnt be completely stational cause scientists have never reached absolute zero, so its just a theory, and theories is constantly being disproved

and isnt 0 k absolute zero means no kinectic energy, not "lowest possible"

[schnappy00]

You did say m cubed in an early vid, confused me a bit as to how that worked out :P

[thebaronb]

i believe 100 F is the body temp of a healthy race horse, 0 F was the coldest temp they could create in a lab at the time.

[leglessl0]

If p1. v1/ T1 = p2.v2/ T2 is this different for different types of gas?

[honesthua]

Very gd explanation about the Celcius scale and Kelvin scale.

[crackfe]

isn't 0° kelvin = -273°C (not -173°C) ????

[naduyn]

yes its 0 K = -273 C

[yuehswind]

he said/wrote that

[TankaFrank]

-273.15°C :)

[omogaju]

he actually said 273...I suppose the tool he is writing with is what makes the 2 look like 1

[schnappy00]

Looks like he does the loopy twos - but the loops aren't big enough so they look like ones. Also the curved bit at the top looks straight.

[DoctorYoon]

is anybody else studying this as a summer hobby besides me?

[yuehswind]

ME!

I'm in my sisters account...

[Jtking3000]

@doctoryoon

YES! LOL

[minooo44]

@khanacademy Sir you are wrong , you convert to Kelvin because you will use constant "R" and in constant R you have to convert it kelvin so that you can cancel unites . or maybe i'm wrong ? can you clarify it for me .

[dalcde]

@minooo44 Kelvin is the SI standard unit of temperature. It's good to use Kelvin in science, but not in daily life. It is impossible to use Celsius or Fahrenheit , since it would allow negative PV, but we know pressure and volume couldn't be negative, so it follows that we should definitely not use Celsius or Fahrenheit.

[yellowmetalcyborg]

@DoctorYoon You are not the only one. I'm working on a stirling engine that will work with helium gas. These equations will help me out a lot. Thermodynamics FTW!!!!

[bestmistake2B]

@DoctorYoon I am haha I actually Already took the class but decided I would see if there was anything I missed during my sleeping through lecture days

[s2daid]

Why does Wikipedia show something totally different when I search for Thermodynamics in it ? Where can I learn about Thermodynamics from its base ?

[captainspiwtf]

Kudos. You are amazing.

[azm1987]

dude you are awesome. you helped me get an A on my last exam an I am in calc-based physics on the university level. i am reviewing for an exam on thermo tomorrow and you are 100 times clearer than my prof could ever be!

[neverwoke]

Your doing a wonderful job...really really wonderful! But why have u stopped the Thermodynamics series? You mentioned in Video 1 that "we ll talk about entropy later on" but that never happened :(

[kemooloove]

really thanks

[rick7917]

Thanks

[Max11551]

As always really helpful. Thanks.

BTW, originally 0°F was chosen for the lowest measurable temperature at that time (frozen seawater), and 100°F was chosen for the average temperature of a human body. (Wiki)

[JohnHolmes3000]

That is correct. Farenheit's calculations of the human body temperature were however slighty innaccurate, which is why Americans get a bad name for using his scale.