You could use the expression delta U = Q-W with the following convention: Q is + if it is added to the system Q is - if it is removed from the system W is + if it is done by the system W is - if it is done to the system.
@@zedusfurkan169 I mean, it's all in perspective, W is - if work is done to the system, but you write dU = Q + W so you get dU = Q + (-W) and then you again get dU = Q - W, so basically both is correct, it's about perspective.
I took a quarter of engineering thermodynamics and you clarified a topic I didn't understand all quarter in this video. Keep in mind, I got a B in the class but I only knew how to solve problems, but I wouldn't be able to explain it to you. Understanding> Grades
u could say for (delta)U = (delta)Q + (delta)W where (delta)Q = (heat given to the system) - (heat taken away from the system) and (delta)W = (work done on the system) - (work done by the system) This way you can just plug and chug instead of tying to figure out the signs of Q and W
This is so awesome, thank you so much for doing this. I find it difficult to read textbooks with full concentration, and it's quite boring after some time. But these videos literally drag me into fully and it's so fun even. The only thing that's bad about this is that I accidentally started to watch videos unrelated to my subject which I'm studying for, lol. You're a great teacher, man.
Thank you so much. That's awesome. I have become convinced that science is a language. You run into problem only if you fail to understand what it is saying. I feel like beginning all over again my tortuous journey into physics with you by my side.
awesome videos! it would be amazing if you could post videos of more advanced thermo! thanks for your videos! they definitely help me remember my basic chem
Khan acadmy is my Life Saver! Thermodynamics freaks me out and these basic videos just clear all concept i hope khan acadmy will make on more complex thermodynamics topics Thankyou Sal khan! Your amazing
Nice to meet you.I am a secondary 2 student. Do we need the unit joule with the answer of internal energy changed?or with the answer of heat or work?^^
No mistakes in the universe, it has a fail safe system embedded in everyday reality. Easy to see and feel as a super genius, it only works one way, life itself is the unified theory of the universe, that is why life is only found in one location.
Dear Sir: I enjoyed your presentation but there is a small thing went wrong. You states at least once at 1.06 that ' I can tell you what the internal energy is' , the internal energy is immeasurable quantity, we can measure the change in internal energy only. My Kindest Regards
ANyone having trouble with the work done on ... vs. work on the system. think where the energy is going. Gas expansion work done on surronding because energy is attempting to increase the volume space
Hey Sal Great video, as usual. I was just wondering if the internal energy also includes the rest mass-energy (E=mc2) of the gas atoms. thanks in advance
I am really confused. Other youtube tutorials used U = Q - W initially. For example: what is the change of internal energy in the system if 300J of heat is added and 200J of work done on the system. In analyzing, Q is +300J while W is -200J. For other tutorials, they used the formula: U= Q - W, hence U = +300 - (-200J) = +500J. While the tutorials here, the formula will based on the analysis, hence: U = +300J - 200J = +100J. What is really the correct way of solving internal energy? Thank you for your time.
Heat is transfer of energy from or to the system. Heat isn't like internal energy. There's no particular amount of energy from the internal energy of the system that can only be transferred as heat and some other other amount as work. So, that's why you can't measure the heat of the system. Heat is not an inherent property of the system like energy is. Energy is like money and heat and are work are like apples and oranges. You can buy apples with money, but you're exchanging it for money, you don't actually have apples until you exchange it with money. The equation Q = ms(T-t) is to the measure of energy that will transferred from or to the system due to temperature difference, but it is not the heat present in the system. Hope this helped.
Amjad Mohammed: -w/+w are correct. it depends on the view point of the chemists and physicist. Chemists analyze it through the system and Physicist through the surroundings.
Alright, I just noticed the smiley face in the "o" he did on accident in the word "done" at time #t=13m15s. If you noticed this or just now saw it, thumbs up!
I'm confused. My professor said that WORK DONE BY THE SYSTEM IS POSITIVE while WORK DONE ON THE SYSTEM IS NEGATIVE. Contrary from what you're saying. somebody Please help
Darren Mayo if work is done by the system on the surrounding then the energy of system decreases therefore the workdone is taken as negative and if the work is done by the surrounding on the system then the internal energy of system increase that is why workdone is taken as positive
If you are using the Formula "ΔU=Q+W".....so when the system does work,it loses energy,so Work is negative,if it's done by the surrounding(to the system)it's energy increases,so the W in that formula is positive........your professor isn't wrong if you are using the Formula "ΔU=Q-W"
You could use the expression delta U = Q-W with the following convention: Q is + if it is added to the system Q is - if it is removed from the system W is + if it is done to the system W is - if it is done by the system.
You could use the expression delta U = Q-W with the following convention:
Q is + if it is added to the system
Q is - if it is removed from the system
W is + if it is done by the system
W is - if it is done to the system.
@@zedusfurkan169 that comment is literally from 9 years ago.
Iol
@@zedusfurkan169 😂
@@zedusfurkan169 its actually correct, ALGEBRAICALLY AND PHYSICS PLAYS WITH ALGEBRA
@@zedusfurkan169 the comment is correct, W is + is work is done by the sistem, and W is - if work is done to the sistem
@@zedusfurkan169 I mean, it's all in perspective, W is - if work is done to the system, but you write dU = Q + W so you get dU = Q + (-W) and then you again get dU = Q - W, so basically both is correct, it's about perspective.
you work to help us understand the concepts instead of just memorizing them. HUGE DIFFERENCE. THANK YOU
I took a quarter of engineering thermodynamics and you clarified a topic I didn't understand all quarter in this video. Keep in mind, I got a B in the class but I only knew how to solve problems, but I wouldn't be able to explain it to you. Understanding> Grades
Bank analogy was brilliant!
me too
Mr Khan finally I figured out the diff between the two equations, thank you very much. Please make some videos on learning programming
u could say for
(delta)U = (delta)Q + (delta)W
where
(delta)Q = (heat given to the system) - (heat taken away from the system)
and
(delta)W = (work done on the system) - (work done by the system)
This way you can just plug and chug instead of tying to figure out the signs of Q and W
This is so awesome, thank you so much for doing this. I find it difficult to read textbooks with full concentration, and it's quite boring after some time. But these videos literally drag me into fully and it's so fun even. The only thing that's bad about this is that I accidentally started to watch videos unrelated to my subject which I'm studying for, lol. You're a great teacher, man.
A helpful acronym to remember for the sign conventions of work and heat is "HIP to WIN". Heat in positive, Work in negative.
Thanks
Thank you so much. That's awesome. I have become convinced that science is a language. You run into problem only if you fail to understand what it is saying. I feel like beginning all over again my tortuous journey into physics with you by my side.
Q = Energy gained by the system.
W = Energy lost from the system.
U = Total energy of the system before losing or gaining energy.
hi
very good job, really easy to understand even for not mother-tongue speakers...
awesome videos! it would be amazing if you could post videos of more advanced thermo! thanks for your videos! they definitely help me remember my basic chem
I thank god everyday that i found your chemistry videos. Thank you. Thank you. Thank you.
Khan acadmy is my Life Saver!
Thermodynamics freaks me out and these basic videos just clear all concept i hope khan acadmy will make on more complex thermodynamics topics
Thankyou Sal khan! Your amazing
freaking awesome video this saved my life.
Wow, I'm watching ALL videos.
Very Smart explaining thank you very much
Nice to meet you.I am a secondary 2 student.
Do we need the unit joule with the answer of internal energy changed?or with the answer of heat or work?^^
nice and free
No mistakes in the universe, it has a fail safe system embedded in everyday reality. Easy to see and feel as a super genius, it only works one way, life itself is the unified theory of the universe, that is why life is only found in one location.
first time i actually saw the colour choosing box
it made a ton of sense
helpful, thank you
Dear Sir: I enjoyed your presentation but there is a small thing went wrong. You states at least once at 1.06 that ' I can tell you what the internal energy is' , the internal energy is immeasurable quantity, we can measure the change in internal energy only.
My Kindest Regards
sorry for the ignorance but what could be an example of "system"?
say the coolant in a car engine. as the coolsnt flows around the engine and to the radiator it transfers energy etc
so basically any fluid, usually contained
zsolt tildy Thank you!!
André Tosatti
in my book, it says that system just refers to a body that is the subject of study.
it can be the earth as a whole or just an atom
André Tosatti
in my book, it says that system just refers to a body that is the subject of study.
it can be the earth as a whole or just an atom
Sal,
If you assume Q=0 and W=0 doesn't it make sense to use the delta?
ANyone having trouble with the work done on ... vs. work on the system. think where the energy is going.
Gas expansion work done on surronding because energy is attempting to increase the volume space
Hey Sal
Great video, as usual. I was just wondering if the internal energy also includes the rest mass-energy (E=mc2) of the gas atoms.
thanks in advance
Not included
At all because we are assuming energy can't be created or destroyed and mass cannot be created or destroyed
OH THANKS GOD GOD YOU WERE BORN!! you have a wonderful method if i continue watching your videos i can Guarantee the A+....... ! :D
Super explanation
I just really like you and your videos man!
Just think of the system as a boiler and walah you understand everything about thermodynamics
does internal energy increase in a phase change?
ame zakire yes
thank you
Q and W are not state functions so they can't have a delta.
If the volume is not constant then how can we find out eternal energy?
Pllzzx reply
really help me huhu
Very nice
What is efficiency of aneroid barometer ??
I am really confused. Other youtube tutorials used U = Q - W initially. For example: what is the change of internal energy in the system if 300J of heat is added and 200J of work done on the system. In analyzing, Q is +300J while W is -200J. For other tutorials, they used the formula: U= Q - W, hence U = +300 - (-200J) = +500J. While the tutorials here, the formula will based on the analysis, hence: U = +300J - 200J = +100J. What is really the correct way of solving internal energy? Thank you for your time.
work done to system means added energy to the system, so 300 + 200
plz make some new videos on thermodynamics because all these are not enough clear. i am referring the video quality.
Just a confusion: You said we cant measure Q of the system.. But cant we measure it by the formula Q=ms(T-t)
Heat is transfer of energy from or to the system. Heat isn't like internal energy. There's no particular amount of energy from the internal energy of the system that can only be transferred as heat and some other other amount as work. So, that's why you can't measure the heat of the system. Heat is not an inherent property of the system like energy is. Energy is like money and heat and are work are like apples and oranges.
You can buy apples with money, but you're exchanging it for money, you don't actually have apples until you exchange it with money.
The equation Q = ms(T-t) is to the measure of energy that will transferred from or to the system due to temperature difference, but it is not the heat present in the system.
Hope this helped.
Mercyritz13 Thanks. That helped a lot!! :)
The people on the Nobel peace committee don't seem to know what creates peace. Sad.
very helpful !
can u state the next videos please
its sometimes hard to find
great work !! :D thx !
Whenever I am bored I come here to meet some smarter people.....😅
Thank you and explanation for thanks ok
y was work done ( in the first problem) taken -10 While the work done was on the ballon, so it should be positive 10 ?
doubt
Yeah it got me really confused. My lecturer also said W is positive when work is done by the system
work was done by the balloon according to the question. So, it is negative in the first equation! got it? :)
The work was done by the balloon .. so it's minus 10
@@RacingEnigma that's sometime used in physics .. but acc to iupac rule .. it's negative if done by system .. mostly used in chem
You hold the same status to students as the status that god holds to its believers.
Isn't work done on system is -ve? If 1 j of Work is done on system by sorroundings.. isn't U= -5-1 which is -6 J
He might be referring the case of system doing the work on its surrounding
so delta T is equil to Q?
1:22 my god that UI gave me flashbacks
the correct form
U=Q-W
Amjad Mohammed: -w/+w are correct. it depends on the view point of the chemists and physicist. Chemists analyze it through the system and Physicist through the surroundings.
@@antoniolee7330+ when work is done on the system and - when work is done by the system
it is so useful for an eight grader like me .thank you so much
Alright, I just noticed the smiley face in the "o" he did on accident in the word "done" at time #t=13m15s. If you noticed this or just now saw it, thumbs up!
👍👍👍
hi
whts this video doing in the chemistry playlist?
Top g, is that you?
*cheque
I'm confused. My professor said that WORK DONE BY THE SYSTEM IS POSITIVE while WORK DONE ON THE SYSTEM IS NEGATIVE. Contrary from what you're saying.
somebody Please help
Darren Mayo if work is done by the system on the surrounding then the energy of system decreases therefore the workdone is taken as negative and if the work is done by the surrounding on the system then the internal energy of system increase that is why workdone is taken as positive
If you are using the Formula "ΔU=Q+W".....so when the system does work,it loses energy,so Work is negative,if it's done by the surrounding(to the system)it's energy increases,so the W in that formula is positive........your professor isn't wrong if you are using the Formula "ΔU=Q-W"
write more neatly please
Despacito
Is it wrong to write : Δυ = q +|w| ?
Yes
You could use the expression delta U = Q-W with the following convention:
Q is + if it is added to the system
Q is - if it is removed from the system
W is + if it is done to the system
W is - if it is done by the system.
thank you