Kinetic molecular theory of gases | Physical Processes | MCAT | Khan Academy

Created by David SantoPietro.
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[@alanbautista9247]

You did a better gob at explaining this in 15 minutes than my professor in 3 weeks. Thank you!

[@Vultimo]

same here!

[@evastatrmercer4357]

Same for me !

[@evamartini2478]

My teacher tried it in 15 minutes as well and that did not work out

[@juzzgail6]

3weeks?????? My professor kust gabe us random worksheets lmao. no discussions

[@teenagegamers8015]

My private teacher in 13.5 mins

[@JoshuaSalazarMejia]

The best explaination that I've found over the web, thanks! You're an excellent teacher David!

[@trappraizzy]

its been 7 freaking years and this is still helpful, thanks man.

[@dad7547]

This is quite literally one the best Physics videos out there. Gave me goosebumps learning about this :)

[@manareldredy9820]

it's the perfect way to explain it i've been skippin phy lectures and watchin vids instead cuz when i watch these vids i understand the subject well and the best of all i don't fall asleep

[@RahulYadav-ix8ky]

delta t should be the time taken for the change in velocity bw the collision on the surface of wall my doubt

[@siuharry5881]

Same here.

[@cosettegarzon5322]

I was so distracted by the cube doing the weird optical illusion thing

[@Zeegoku1007]

Yeah , same.

[@aboldone3991]

I hate you. I can't unsee it now.

[@anonymous-8259]

so here i am watching this khan's video instead of listening to my lecturer. Tbh its easier to learn here than to learn from my professor and it took me less than 15 minutes to figure out things than listening to my professor for 2 hours session. SO WHY AM I PAYING MY COLLEGE TUITION FEES FOR :((((((

[@stainfxce2303]

anonymous - same here

[@jacobvandijk6525]

@ 8:23 The only thing we get is a formula telling us how to calculate the pressure P when N particles hit ONE SIDE OF THE BOX at the same time. What about the pressure on the other walls??? @ 11:07 Only 1/3N particles are hitting that ONE WALL !!!

[@sunildeshpande6600]

is temperature related to the only translatory motion of the gas molecules or also to rotatory and vibratory motion? if so why do we only consider the change in the linear momentum in the discussion?

[@sickboydroid]

Yeah actually for real gases you have to consider that as well. But for ideal we neglect all intermolecular force and gravitational force so particles always move in a straight line path (called free path). They change directions only when they collide with other particles but after colliding they again travel in straight line path. So you don't need to calculate any other momentum other than linear momentum for ideal gases

[@rifathasan2741]

Oh god... I wasted more than 7 days on this topic none couldn't explain it . At last i got it. Thank you 😍

[@CarlosJimenez-fj4ku]

"It's so important I'm gonna write it again" -David SantoPietro, 2014

[@FangsShadow]

Why isn't this up on the website with the ideal gas equation series?

[@hampirestoration]

Calculation of the pressure of an ideal gas...! It's in HC verma.. but this video makes it even more easy to follow! 😊

[@halo4eva100]

Just went to a lecture and didnt understand most of this stuff, watched two Khan academy videos and everything is so clear to me now. Thanks you!!!

[@jugalshah9261]

Thankyou sir, you helped me understand that why aren't we taking the delta t as the time of impact,, God Bless you

[@theiigotriangularround4880]

For those who don't get why we took time interval instead of Collison time ans what it tells us . Well it gives us magnitude of force as if a force acted on particle as it went from one wall to another wall and back.

[@lytvynenkod]

This explanaition is wrong !!! You can't use the momentan force applyed on the wall like it will be with F= ∆p /∆ t , but you need the average Force applyed on ONE WALL (always the same). So you have to calculate the total momentum over the time (F_average=p_tot / time_tot) and to dothat , you make a sum over all the momentum diveded by the sum of all times. => F_average = (-2 p_x (t_contact ) + 0 (t_travel)) / (t_contact + t_travel) = (-2 p_{x} (t_contact ) / (t_contact + t_travel) , the 0 is the momentum aplied on the wall for time that particle is away from the wall (t_travel ). since t_travel >>>>>>> t_contact YOU GET F_average_ = (-2 p_{x} (t_contact ) / (t_travel) This detail is very important for the logical construction of the solution , otherwise you learn wrong concepts.

[@lincolndexter9514]

thank you

[@EigenPhys]

thank you, you cleared my confusion

[@sickboydroid]

OMG! That was a great explaination (especially for the last part) You are a life saver dude... Love from India ❤️

[@percyjacks8170]

Simply amazing! I understand it a lot better now, the use of colours really helped too :)

[@pavanibukya8823]

Ohhhh

[@xigong3009]

The mentioning of the link between macroscopic and microscopic quantities is great!

[@emanalwan6461]

Something didn't make sense to me. when we talk about change in momentum isn't delta t the time spent in the collision itself why would we use the time between two different collisions?

[@Marisa-mv4cw]

i've been relying on KZbin explanations for my finals lol Khan Academy did a stellar job at explaining every single subject. propsssss.

[@user-hc6tk3vz9d]

this is fantastic, really love it

[@ccl051485]

Very clear for me understand

[@MohamedGamal-rv3cm]

Question, How come we use delta P = 2 mVx , and the V here is for velocity then you used v= x/t where V here stands for speed not velocity and took its valuue to plug it in the delta P = 2 mvx . explanation please?

[@aniljyotir9788]

It was so much fun to learn it

[@Seishiro_Nagi_11]

Can some one answer me the air density is less in higher altitude that of lower altitude meanings , gas molecules due to effect of gravity have more density and form lower layer of atmosphere in more amount. It is against one of the postulates of KTOG of is the assumption wrong!?

[@ryanmagbitang7545]

you racists fker

[@segasaturn3215]

Are you assuming that all particles are traveling in a straight line from one end of the container to the other by using 2L as the distance?

[@chibuikeagba8591]

I wish I saw this before today. Thank you very much for making me understand this.

[@jexk2985]

I don't understand why velocity in this lesson equal to distance over time please anyone answer ? And why did the displacement equal to 2L?

[@SkylerWhiteYoo]

Man, you are amazing! Thank you!

[@muddyagua]

thx for making understand the 1/3 in this formula which my professor just wanted me to memorize mechanically

[@mariumali4852]

I still don't get the reason given at 4:15

[@samsunnahar9175]

Thank you so much for your excellent explanation!!

[@babulroy3093]

Very clear presentation.

[@harsh8457]

Superb video Thanks for clearing bdoubt

[@ahmedsalem4675]

These very helpful

[@ms32chiacaixin75]

Thank You !

[@fadelsmida7151]

I like this guy

[@togrulnbili8703]

that is exactly what i was looking for.Thanks for great explanation

[@user-ic4uz8ee9x]

thank you so much for your kind and sophisticated explanation !

[@zabintanfa7650]

It was really very good and helpful.

[@TheKing-th1en]

Great explanation.good job 👍🔥🔥🔥

[@violat6549]

really helpful

[@hypercuriosity9828]

Thank you 😊

[@samsonodoyo8144]

amazing explanation David

[@geetathakur445]

Thank you thank you thank you!👍👍👍👍👍👍

[@HorizonSpeed26]

Very nice and interesting presentation.

[@mahaboobbashashaik148]

Can you please also make a video explaining the derivation in the first chapter of Max Born's Atomic Physics for same equation?

[@taromellon]

THANK YOU

[@jasonlosslow2423]

good explanation as always Thx khan academy

[@Calvin3578]

I AM GOING TO HAVE A PHYSICS EXAM IN THE COMING WEDNESDAY. THIS VIDEO IS REALLY AMAZING! THANK YOU SO MUCH BRO!

[@sarahkaveh7739]

It was 5 years ago 😃i just wonder what your career is now or what you are doing

[@vigneshsubash8970]

Thanks for your video! Seriously helped a lot.

[@a7mad3bbas]

wow !! really appreciate it ! .. such an awesome explanation!!

[@frankgetachew1833]

You're my best

[@eccleziassenat3262]

great explanation i love it.

[@arcollaboration9380]

The explanation made me like and share he video

[@starkkyr7976]

thank you khanacademy

[@saivarun656]

It's too simple my teacher was explaining this in a quite complicated way that I just.....dozed off😴😴😴😝😝

[@muhammad.husnain6819]

u are amazing mate

[@nithishreddy1690]

excellent boss

[@jazirusharifu8393]

good presentation

[@thaison7332]

ty sir

[@ottoomen5076]

excellent presentation. Does anyone know of any molecular theory of gases books?

[@ewoigbesamuel5558]

Nice❤️.

[@Mooloolah28]

Thanks man, like always.

[@thinhl8683]

Is this on Khan Academy Website?

[@stonebrother3751]

Wallahi you are awesome :D

[@hritikgogoi3577]

I become your fan. So nice... 😇

[@jagratsingh3664]

It will take longer then 2l as there are intermolecular collisions also increasing time

[@prathameshnakhawa4975]

I have a doubt if we assume that total p particles are there and then we say n number of particles collide in the right plane in x directionand say some x particles collide in the upper plane in y direction then how is the mean velocity is same ux= uy=uz

[@Jaideep_Joy]

Wow amazing explanation you made it look really easy....

[@kevinpham597]

+jaideep sohal Seriously. What I love is how he says how awesome each equation is and then explains what they're supposed to mean.

[@zayaanpandi7538]

why do your pic have the MIDDLE FINGER :(

[@technodeus1122]

There are two fingers lol... It doesn't have just middle finger

[@drakerocky7808]

thanks

[@eshakurwa]

Sincere thanks. You made my day. Concepts cant be cleared any better :-)

[@ayushd5430]

Hlo

[@joza-bi3iz]

Algebra God!!!

[@mikomurray1661]

I loved this video. You explained it so well and made me pretty excited about doing some maths in the process! Nice work :)

[@DfitDoc]

I did fifteen pushups for you

[@brianbycroft6090]

In the macroscopic world, if it was a ball bouncing against a wall, to calculate momentum change, and thus force, the delta(t) would be the time in contact with the wall, not total travel time. For much of the time period 2L/v, there is no momentum change. Why is this larger time period used at the microscopic level??

[@brianbycroft6090]

+Brian Bycroft Makes perfect sense, after I read the notes on the video! My apologies

[@elangz9201]

Brian Bycroft can u explain it to me pleasee

[@danehas4078]

Brian Bycroft which note?

[@justpauify]

Help please

[@mazenmohammed3262]

Thanx

[@kayannahall5723]

God bless you :)

[@saskiakristofedes9836]

There r 10 concepts of KMT of gases right? could u explain those individually?

[@shubhanshu4889]

thanks a lot bro you just saved me from failing

[@danehas4078]

Still dont get why DeltaV = 2V And why delta t has to be 2L/t when when it is traveling from side to side without acceleration.

[@danehas4078]

TheFsxChannel201 if its vector, then why doesnt it = 0 when the V looks like it finally go to the starring place

[@danehas4078]

TheFsxChannel201 starting*

[@khushalsiddiq7852]

How do you work out Vx2 average.

[@sudhapriyashrivastava6808]

Please explain why Velocity in x,y,z directions are equal.

[@abenphilip4283]

Since the gas is isotropic...(having same proper ties in all directions)

[@amansinghal2431]

just a curious question what are u using to write because it looks like handwriting but I can see the cursor?

[@kashishkhandelwal9592]

Smoothdraw 4

[@mihaimi9978]

Ideal gas with: P=10^5Pa V=2 l What is the average kinetic energy of translational motion of the molecules of this gas?

[@AnkitaMazumder24]

Mihai Mi Either number of molecules of gas or number of moles of gas is required to solve it.

[@kay-wh8gq]

Man you killed the shit outta the topic.

[@mhmmdhaggag]

hiiiican you tell me please what ddi you use to make this video what is that tool you use to appear on screen like a black board???

[@RogueNiNja99138]

+Mohammed haggag Sal uses SmoothDraw v2.1

[@vintagescorpio49]

+manuveer singh and movtavi, and microsoft paint, and... yea

[@SO-dl2pv]

You should use integrals instead, to make a good lecture

[@marcusw3541]

I'm still learning this. How are integrals involved? we didn't discuss it in class nor does my book mention it in deriving the theory

[@SO-dl2pv]

Actually the advanced material will be found in The theory of kinetic gases

[@marcusw3541]

Ok cool, I'm probably far from understanding it lol Btw, random but curious question, are you in a specialized field related to thermodynamics/physics? And if you happen to be, what's your drive man? I mean I find this sort of stuff abstractly fascinating, but it's just a drain to fucking work on and understand.

[@SO-dl2pv]

:) every thing is possible dude

[@Aerosmissive]

please someone let me know the difference of Energy of Electron kT between molcule E=3/2kT

[@Lynx-ps7kg]

❤❤❤

[@akashghorai2804]

Like it

[@zainabhussain3887]

💜

[@AnkitKumar-xr8yc]

why are we adding all N molecule forces at a same time because all the molecules of gases cant hit the face at same time please answer

[@TheLogmp]

+Ankit Kumar Great question. It's a fine point, but he adds all the particles at the same time because if you remember when he was replacing delta t, he stated that delta t was the time interval for a particle to collide with the wall, bounce off the parallel wall on the other side, and then come all the way back. That means every particle will eventually collide with the wall during that time interval. There are alternative derivations where you leave delta t and apply it to the number of molecules moving rightward at a given time, in which case you do divide by one half (because half are moving rightward the other half are moving leftward), which is what you were probably thinking to do. That method is also completely fine and you arrive at the same answer. I prefer that method because you don't have to arbitrarily multiply by one half to see the kinetic energy term. It's there from the beginning. :)

[@johngasno4602]

"Great explaination" it's so important I'm gonna write it again

[@marcusw3541]

[@SBB628]

we have assumed that the walls of the container are elastic for molecular collisions. actually the walls may be inelastic. why does this makes no difference as long as the walls are at the same temperature as the gas?....answer plzzz

[@tmb0183]

The weight of the gas molecules is very, very less compared to that of the container that their collisions don't create an effect on the container. moreover due to this they get rebounded with the same velocity

[@AnkitaMazumder24]

You may want to study the assumptions made for an ideal gas to derive these equations.

[@edis9493]

Why is N not divided by 2 as well?