nah its bad this way cause imagine if we clicked on a trash vid but we had to wait a solid 5 mins to realise it rather than have the like dislike ratio tell us beforehand@@namename3130
I got my A-levels this upcoming October and I'm really glad that there are some people like this gentleman here who help students for free!! I wish the best for you teacher, and thanks a lot for the videos👌
Your videos is the most helpful resource I have for physics. I would be lost without them truly. Thank you so much, I'm glad that you are here making these.
These videos are so great thank you! It saves so much time rather than plodding through a textbook and it is really enjoyable listening to someone speaking and drawing nice diagrams.
i pray for ur well being and success in ur future endevours.. u are a legend and the unsung hero for many students.. keep making these videos for students like us to whom the text book or class lecturer doesn't seem to make any sense..
I couldn't understand this trough notes and i searched for so many videos and i understood none until i got to this one. You put thermodynamics so simply into words, really well done and thankyou so much for your help!
Many thanks learned this topic remotely over lockdown and I’m not gonna lie it made very little sense in the lessons so I tried reviewing the PowerPoint and it ended up just making me more confused but this really helped :))
Have in mind 3 in kinetic gas theory stands for 3 translational movement vectors, each is perpendicular to each other (vectors along x, y, z) axes. This formula is only used in ideal gas systems, where a molecule is made from one atom
Other types of gasses store energy in molecular rotation and vibration, which is why molar heat capacity isn't identical for all types of gas. Otherwise it would be.
In the beginning of your derivation, what sets the first particle in motion? I understand the particle gets KE but from where?? What force causes this?? Im so confused
what i dont get at all is when deriving pressure formula we only consider it acting in a single dimension when pressure acts in all directions so how is that the total pressure?? someone pls helpp
Great video. Just one problem though: the momentum of a gas molecule is p=mv, so the change in momentum is mv-(-mv). So that would be 2mv, I don't understand where the negative sign came from in the force equation. Edit: I realise you said that you get rid of the negative sign as it doesn't really matter too much, I was just confused.
It's because change in momentum is calculated by momentum *after* - momentum *before* . So if a particle is initially travelling at v and ends up travelling at -v, then the change in momentum is (m)(-v) - (m)(v) = -mv - mv = -2mv. Hope that helps?
@@DelboiixHello , shouldn't time be l/u instead of 2l/u for one collision. Why 2 is there ? Also , if particle hits one wall , why are we taking whole area of six faces
Sir, I love the video but there's just one thing I am confused about. Isn't force equal to the change of momentum over the "time taken *for* the collision", and not the time between two? I mean, if I am incorrect, please rectify my mistake. I'm just really confused about this part.
I know this is probably going beyond the curriculum but does this only apply to gasses in a cuboid? What if the shape of the container is different? Is there a way of deriving this equation for irregular shaped containers?
at 9:50 you equated density to p = Nm/V or (#. molecules * mass)/Volume I'm confused where the #. of molecules comes from here, or if density is different for a gas?
what do you mean when u say Duration of collisions is very short compared to time between them, do you mean the time it takes for the particles to collide?
Thank you for the explanation sir it is really helpful but at 7:56 how did you proceed to root mean square speed from mean square speed ?? please explain, I googled it but coudn't find any solutions
When the gas is in equilibrium , molecules moves entirely random. So all the direction of motions are equally probable. so , u(mean square)=v(ms)=w(ms)=( u^2+v^2+w^2)(mean)/3=c(ms)/3
So based on the fact that we use for time the time that it takes to travel back and forth, this means that the force we obtained it is not the force during the impact but it's the AVERAGE Force that is felt during the whole back and forth translation, the force THAT is felt by the particle at every point during it's translation, is my understanding correct? Please answer.
Sorry, I'm a little confused, at 10:20,why did you combine 1/3 and 1/2. 1/3 only relates to particles moving in the u(or v or w) direction whereas we are trying to find the kinetic energy of a single particle. So why?
Hi i have never seen the questions of edexcel board ask for equation like that of at 11:27. So I am a little confused as its not matching my specification.
If u look at 5:10 dimension lx is already included in the equation for force. Given that pressure=F/A, A=lylz and this combines with lx which is already in the force equation to give lxlylz which is the volume.
I am from nepal.And i also study science.Physics is a logical subject.So, it needs a lot of hardworking and concept.Thanks you sir for make this video and i am capable to study this.
Thank you so much! I have a question, are we assuming that the container is a cube ?? because i think just so can (Vx)^2=(Vy)^2=(Vz)^2 = (1/3)(V^2)... if that really is the case, how can we still apply this equation in situation when lx are not equal to ly and lz (not a cube) ??. Somebody please explain, thank you!
The cube is only a model we use to derive the equation. It still holds true for any container, as there will always be as many particles going up, down, left, right etc.
@@ScienceShorts Omg, thank you so much 😭 I was being stupid, I was looking at the equation for average Force overtime and wonder why on earth could F be equal in each x,y,z case if the length of each side is not equal. Turns out you were talking about Pressure and only after dividing the equation by Area did we generalize the velocity square average!! Thank you so much for the video and for your reply !!
@@ScienceShorts I usually see this derived using calculus conventions, using dx, dy, dz differential elements instead. Your method is mathematically equivalent, without confusing students who may not be familiar with deriving things using calculus.
A container of volume 0.7m3 holds oxygen gas at a pressure of 4.0 × 105 Pa and a temperature of 288K. (Relative molecular mass of oxygen gas = 32.) Calculate: (i) the number of moles of oxygen gas in the container; (ii) the rms speed of the molecules. Someone help me and explain this please!!! Much appreciated
1 year late.. lol but for the second part you can use equation pV=1/3Nm(crms)^2 Use the value of moles you got in part 1 nR=Nk Rearrange nR/K =N Then find mass of oxygen: Relative molecular mass x moles= mass Insert values into equation : (pV/(3)Nm) =(crms)^2 Square root answer And then you have (crms)
@@user-ej6we6ei7q momentum is a vector quantity change in momentum would be final momentum - initial momentum consider momentum to the right as positive, then final momentum = -mu1, initial momentum is mu1 hence change in momentum = -mu1-mu1 = -2mu1 then rate of change of momentum = -2mu1/t
well before anything i think he meant to represent the gas as a whole by just that one partical...but again he also mentioned that there are many other individual particals and he was clearly referring that while deriving the equation so i am as confused as you
wait i got so confused by a point...so why did you assumd that the area under force is the whole area of one face of the box which you suggested to be lz x ly. does that mean that one single partical is as big as the box which does not make sense at all?
@@ScienceShorts So if I punched a gigantic wall that gigantic area, does that mean the pressure I exerted is P=F/Area of the entire wall ? Contradictory to what we've learnt about pressure isn't it?
@@ferdousreza6907 There's billions of gas molecules. This is simply the force on one face of the container, due to the "average" gas molecule. I.e. the gas molecule moving at the RMS speed specifically.
Listen science short I am ordering u - please make more such awesome Videos, these help me too much in my exams so u have to help me and make more vidoes or I will find u .....and beg u to do so
@@Holly-ew7ps cos change in p = final p - inital p. Initial p = mu, Final p = m(-u) = -mu (because the final velocity is in the opposite direction of 'u', thereby '-u') So change in p = -mu - mu = -2mu 🙃
If you multiplied the 1/3crms^2 = kT by 3, you get crms^2 = 3kT. so then you put crms^2 into the second equation, which is 1/2crms^2, meaning you halve the 3kt, making it 3/2kT. I'm not sure if I explained it well.
@@krishnabhambhani5270 We can account for dropping the negative sign using Newton's third law. -2mv/t is the force needed to change the momentum of the molecule and so is provided by the wall and acts on the molecule. The force on the wall, using Newton's third law. is equal in size and opposite in direction. This means that the force we want is positive.
And if yes how does it apply to the single moving particle's momentum because if the particle goes in a direction w momentum mv and comes back with the same momentum but with -ve momentum (-mv) wouldn't it be mv + (-mv) which is 0
For the change in momentum over the change of time why do u use 2l when calculating the change of time? Shouldn’t change of time = to the time of impact not the time between two collisions on the wall. Really confusing.
This is so we get the maximum time within which the collision happens. To get the average force, we need to take the change in momentum and divide by the total time this happens over, seeing as the impact time itself would be infinitesimal.
i know its silly but do these teachers have to use these markers to write on paper? it makes me tingly and i get goosebumps throughout the whole video. its still a great video and explained the theory really well and i really appreciate that, just curious bout the markers.
Those 28 dislikes are teachers, amazing video, really helps revision
What 28 dislikes, i see no dislikes. Isnt the world such a nice place without dislikes, everyone likes everything now. Fabulous
nah its bad this way cause imagine if we clicked on a trash vid but we had to wait a solid 5 mins to realise it rather than have the like dislike ratio tell us beforehand@@namename3130
I got my A-levels this upcoming October and I'm really glad that there are some people like this gentleman here who help students for free!!
I wish the best for you teacher, and thanks a lot for the videos👌
How did it go?
Your videos is the most helpful resource I have for physics. I would be lost without them truly. Thank you so much, I'm glad that you are here making these.
These videos are so great thank you! It saves so much time rather than plodding through a textbook and it is really enjoyable listening to someone speaking and drawing nice diagrams.
Thank you! In class I was just writing a bunch of equations not knowing where they came from and you derived it clearly 😊.
YOU SIR, ARE A LEGEND!
i pray for ur well being and success in ur future endevours.. u are a legend and the unsung hero for many students.. keep making these videos for students like us to whom the text book or class lecturer doesn't seem to make any sense..
this is the day before my exam, this helped to get the derivation in my head, thank you
dude you’re single handedly saving my physics a level thank you so much
Anyone watching the night before the Paper 2 exam?
Callum Grimes guilty 😂
Same here. I have a strong feeling Gases will come up tomorrow
Absolutely shitting myself Grimes XD! good luck ladies and gents!!
me im super anxious
Hope this comes up the only thing I know😭😭😭😭
I couldn't understand this trough notes and i searched for so many videos and i understood none until i got to this one. You put thermodynamics so simply into words, really well done and thankyou so much for your help!
Extremely detailed!! I've solved more than 25 exams in the past papers and they aren't ever that detailed!!
insane how easy you made this incredibly difficult topic to understand, thanks!
Best A2 physics gas derivation vid approval from S.Korea
Raved is a life saver. Thanks
Many thanks learned this topic remotely over lockdown and I’m not gonna lie it made very little sense in the lessons so I tried reviewing the PowerPoint and it ended up just making me more confused but this really helped :))
These videos are some of the best and most clearly/thought out videos as it relates to physics as I have seen
Best derivation I've seen so far, thank you!
sat through this with my daughter...really helpful with derivation thanks
Have in mind 3 in kinetic gas theory stands for 3 translational movement vectors, each is perpendicular to each other (vectors along x, y, z) axes. This formula is only used in ideal gas systems, where a molecule is made from one atom
Other types of gasses store energy in molecular rotation and vibration, which is why molar heat capacity isn't identical for all types of gas. Otherwise it would be.
Excellent work, Sir! Your work is very detailed and I appreciate that very much. Thank you!
That was the best sum up of the kinetic theory. Kudos my friend
Pretty sure you just saved my life
very clear explanation of the derivation... thanks
thanks for helping me get through A levels.
sir awesome work just fab
This was so useful! thank you!!!!!
Thank you for this channel so helpful. saving my alevel fr
Thankyou sir its now well understood
In the beginning of your derivation, what sets the first particle in motion? I understand the particle gets KE but from where?? What force causes this?? Im so confused
So helpful, thanks a ton!
excellent explaination
@Science Shorts
This is in IGCSE physics for CIE; a whole section on this thanks!
what i dont get at all is when deriving pressure formula we only consider it acting in a single dimension when pressure acts in all directions so how is that the total pressure?? someone pls helpp
Great video SIR☺
Don't forget the subscript 1 next to the velocity
well explained
Thank you very much for the help would failing without you very clear can u pls make a video on option topic of engineering physics would b great
The only step that is hard accept is the 2lx/u as the time per boundary collision, something tells me it should be on average lx/u
Sir... U are too good in explanations
Great video. Just one problem though: the momentum of a gas molecule is p=mv, so the change in momentum is mv-(-mv). So that would be 2mv, I don't understand where the negative sign came from in the force equation.
Edit: I realise you said that you get rid of the negative sign as it doesn't really matter too much, I was just confused.
It's because change in momentum is calculated by momentum *after* - momentum *before* .
So if a particle is initially travelling at v and ends up travelling at -v, then the change in momentum is (m)(-v) - (m)(v) = -mv - mv = -2mv. Hope that helps?
Change of any physical property is (after)-(before), so it is negative
I had the same question, thanks people in the replies :)
@@DelboiixHello , shouldn't time be l/u instead of 2l/u for one collision. Why 2 is there ? Also , if particle hits one wall , why are we taking whole area of six faces
so helpful, thankyou!!!!
Sir, I love the video but there's just one thing I am confused about. Isn't force equal to the change of momentum over the "time taken *for* the collision", and not the time between two? I mean, if I am incorrect, please rectify my mistake. I'm just really confused about this part.
Yes. But by using the time between collisions, we are calculating the average force a particle exerts as it goes from one end of the box to the other.
@@ScienceShortssir , the time between collisions should be l/u ? Why is it taken as 2l/u , please tell sir.
@@abbasmehdi2923 this might be late lol but its because we consider the particle going TO AND FROM the cube so it travels the twice the length
I know this is probably going beyond the curriculum but does this only apply to gasses in a cuboid? What if the shape of the container is different? Is there a way of deriving this equation for irregular shaped containers?
The cube is only to derive the formula. This can then be applied to any container.
Wouldn’t it be too huge an assumption if you consider the time to be 2l/u?
Ikr
That's literally what I was about to comment... Makes no sense to me :(
wtf this is so true
I can't understand why we use this time interval in order to find the force. Can you please elaborate? Thanks in advance.
It gives the average force exerted by a particle.
A brilliant video, thank you very much!
Thank you sir
u r the best
at 9:50 you equated density to p = Nm/V or (#. molecules * mass)/Volume
I'm confused where the #. of molecules comes from here, or if density is different for a gas?
To get the total mass of all the molecules we do this.
what do you mean when u say Duration of collisions is very short compared to time between them, do you mean the time it takes for the particles to collide?
Time of their actual collisions. While they are together colliding. Compared to time they are apart and not in a collision
Thank you for the explanation sir it is really helpful but at 7:56 how did you proceed to root mean square speed from mean square speed ?? please explain, I googled it but coudn't find any solutions
Its not quite asked or useful the only questions asked are about what the symbol c means
When the gas is in equilibrium , molecules moves entirely random. So all the direction of motions are equally probable.
so , u(mean square)=v(ms)=w(ms)=( u^2+v^2+w^2)(mean)/3=c(ms)/3
Why is I find it easier to understand it from this ,than a book by the exam board?
Superb
So based on the fact that we use for time the time that it takes to travel back and forth, this means that the force we obtained it is not the force during the impact but it's the AVERAGE Force that is felt during the whole back and forth translation, the force THAT is felt by the particle at every point during it's translation, is my understanding correct? Please answer.
Yes, you've got it 😊
@@ScienceShorts cool thanks! 😊
wait why is distance twice the length of the box at 4:28
Sorry, I'm a little confused, at 10:20,why did you combine 1/3 and 1/2. 1/3 only relates to particles moving in the u(or v or w) direction whereas we are trying to find the kinetic energy of a single particle. So why?
c (rms) is an average speed that takes into account of all 3 different directions🙃
De hecho, entendí mas en este vídeo que en mis clases jajaja
How time is 2l/u for one collision? Shouldn't it be for two collisions ? What about y and Z dimensions ? Please tell 😢😢😭😭😭
Hi i have never seen the questions of edexcel board ask for equation like that of at 11:27. So I am a little confused as its not matching my specification.
Kaishary Islam this for aqa
THANK UUUUUUUUUU
I still don’t understand how you got to p=(-mv^2)/lxlylz. Why is the area xyz that should be Volume.
If u look at 5:10 dimension lx is already included in the equation for force. Given that pressure=F/A, A=lylz and this combines with lx which is already in the force equation to give lxlylz which is the volume.
thanks buddy
What happens when solid matter is crushed, smashed, grinded or broken in pieces? How can we explain it using particulate nature of matter?
these videos are the only way im gonna pass my A-levels lmaoo
same
I am from nepal.And i also study science.Physics is a logical subject.So, it needs a lot of hardworking and concept.Thanks you sir for make this video and i am capable to study this.
legend
I still dont get3:08 duratuon part
Why are we cobsidering 2l
Thank you so much! I have a question, are we assuming that the container is a cube ?? because i think just so can (Vx)^2=(Vy)^2=(Vz)^2 = (1/3)(V^2)... if that really is the case, how can we still apply this equation in situation when lx are not equal to ly and lz (not a cube) ??. Somebody please explain, thank you!
The cube is only a model we use to derive the equation. It still holds true for any container, as there will always be as many particles going up, down, left, right etc.
@@ScienceShorts Omg, thank you so much 😭 I was being stupid, I was looking at the equation for average Force overtime and wonder why on earth could F be equal in each x,y,z case if the length of each side is not equal. Turns out you were talking about Pressure and only after dividing the equation by Area did we generalize the velocity square average!! Thank you so much for the video and for your reply !!
@@ScienceShorts I usually see this derived using calculus conventions, using dx, dy, dz differential elements instead. Your method is mathematically equivalent, without confusing students who may not be familiar with deriving things using calculus.
A container of volume 0.7m3 holds oxygen gas at a pressure of 4.0 × 105 Pa and a
temperature of 288K. (Relative molecular mass of oxygen gas = 32.)
Calculate:
(i) the number of moles of oxygen gas in the container;
(ii) the rms speed of the molecules.
Someone help me and explain this please!!! Much appreciated
aavash devkota (I) : pV = nRT
4 x 10^5 x 0.7 = n R x 288
n = (4x10^5 x 0.7)/(R x 288)
and just type that into your calculator
1 year late.. lol but for the second part you can use equation pV=1/3Nm(crms)^2
Use the value of moles you got in part 1
nR=Nk
Rearrange nR/K =N
Then find mass of oxygen:
Relative molecular mass x moles= mass
Insert values into equation : (pV/(3)Nm) =(crms)^2
Square root answer
And then you have (crms)
awesome
Sir at 3:37 , can you explain me the -2mu/t part 😔
Please if u alr done ur alevels and get this please pelase explain it to me, I keep rewatching it and I don’t get it
@@user-ej6we6ei7q momentum is a vector quantity
change in momentum would be final momentum - initial momentum
consider momentum to the right as positive, then final momentum = -mu1, initial momentum is mu1
hence change in momentum = -mu1-mu1 = -2mu1
then rate of change of momentum = -2mu1/t
ok thank u
Why are you considering the area of the whole wall? Shouldn’t it be just the area of contact between the particle and wall?
i had the exact same question
well before anything i think he meant to represent the gas as a whole by just that one partical...but again he also mentioned that there are many other individual particals and he was clearly referring that while deriving the equation so i am as confused as you
Good Luck Guys !!!
Day before exam cba to learn this just going to pray it doesnt come up
Imma just remember the cube ngl
wait i got so confused by a point...so why did you assumd that the area under force is the whole area of one face of the box which you suggested to be lz x ly. does that mean that one single partical is as big as the box which does not make sense at all?
?
No, it means the force exerted by one molecule on a face lylz.
@@ScienceShorts So if I punched a gigantic wall that gigantic area, does that mean the pressure I exerted is P=F/Area of the entire wall ? Contradictory to what we've learnt about pressure isn't it?
@@ferdousreza6907 There's billions of gas molecules. This is simply the force on one face of the container, due to the "average" gas molecule. I.e. the gas molecule moving at the RMS speed specifically.
5:44
Listen science short I am ordering u - please make more such awesome Videos, these help me too much in my exams so u have to help me and make more vidoes or I will find u .....and beg u to do so
Sir yes sir.
ARE YOU FROM KINGSMAN
can you explain to me why you said density= Nm/V and not m/V
m is the mass of the single molecule. so Nm is the total mass of the substance divided by V gives the density
yea i just realised doing Np (p=density) gives the same as Nm/v
M/V here M is mass of gas which is equal to n×m(n=no of molecules,m= mass of each molecule)
so nm/V= M/V
I love you
How can you possibly dislike the video unless you misclick the like button
Do we have to learn this of by heart?
yeee
RT-Viz the kinetic theory model?
ManasChaubey for aqa yes
no u dont, its given in the data sheet
Proof my typewriter is not a calculator
lmfao pls?
why is it minus 2mu?
cant we just say positive 2mu from the start?
idiot
Can someone answer this please
@@Holly-ew7ps cos change in p = final p - inital p.
Initial p = mu, Final p = m(-u) = -mu (because the final velocity is in the opposite direction of 'u', thereby '-u')
So change in p = -mu - mu = -2mu 🙃
😇🤪🤭
@@mrk2938 LOOL
VADER is a better mnemonic to remember with!
Woah! Why didn't I think of that?! 😄
why are we allowed to just remove the negative sign??
We're only concerned with the magnitude.
What do you mean time between them 1:49
face reveal at 60K subs?
well, really nice explantion! I hope I would have watched this earlier.
The smell from the markers would make me sick lol so satisfying tho
Where did the 3/2 in 3/2KT come from?
If you multiplied the 1/3crms^2 = kT by 3, you get crms^2 = 3kT. so then you put crms^2 into the second equation, which is 1/2crms^2, meaning you halve the 3kt, making it 3/2kT. I'm not sure if I explained it well.
Thank u soo.. Much...
Can u again tell me that why we neglected the sign (_) in _mu sqare
Because we just care about the size of the force, not the direction.
@@ScienceShorts and why is that so pleasee??
@@krishnabhambhani5270
We can account for dropping the negative sign using Newton's third law. -2mv/t is the force needed to change the momentum of the molecule and so is provided by the wall and acts on the molecule. The force on the wall, using Newton's third law. is equal in size and opposite in direction. This means that the force we want is positive.
@@peterwilde4022 so that means -ve force (due to direction) = +ve force? If relating to Newtons 3rd law??
And if yes how does it apply to the single moving particle's momentum because if the particle goes in a direction w momentum mv and comes back with the same momentum but with -ve momentum (-mv) wouldn't it be mv + (-mv) which is 0
For the change in momentum over the change of time why do u use 2l when calculating the change of time? Shouldn’t change of time = to the time of impact not the time between two collisions on the wall. Really confusing.
This is so we get the maximum time within which the collision happens. To get the average force, we need to take the change in momentum and divide by the total time this happens over, seeing as the impact time itself would be infinitesimal.
@@ScienceShorts I think he still deserves a clear answer to his question, especially given the emphasis placed on the fact that collision duration
day before physics exam , speed = 1.5
How did it go
@@sosman747 decent , thx for asking
@@tbobxtbob bruh. Thanks for answering. Most just leave such comments and then don't respond
i know its silly but do these teachers have to use these markers to write on paper? it makes me tingly and i get goosebumps throughout the whole video. its still a great video and explained the theory really well and i really appreciate that, just curious bout the markers.
Anyone else agree this is the hardest part of Alevel physics?😭
I will add I am a chemistry teacher and I though it was fab
why the fk is delta(mu)^2=-2mu????
what are the chances of this actually coming up
if it does were all fucked :P
just memorize that shiyt bro
@@Aixzyl No we'll be fine because we have Science Shorts :)
John Onal I think AQA might be horrible to us and put it on as a 5 marker 😂