Even though I have nothing to do with this topic , I just got a notification about it all I wanna say is that It's been a year since this guy gave me an A+ in dynamics . I am still very thankful to you .❤️🌹
For the question at 6:00 Why did we use Cp for oil and Cv for air? Well for air it's understandable since it's in a fixed volume of 50 cubic metres, but the oil is in that fixed volume of the heater as well, right? Why is the volume then considered to be changing here?
Actually, it doesn't matter, since the value was given, whether it's cv or cp. You can make cp to be cv, and assume it to be a constant volume as well. It really only matters if you have to look up a value in a table. 👍 For the room, your statement is correct, it is a fixed volume since there are no air leaks, which is why we looked for the cv value.
@@akshatverma3529 No, that's not what I said at all. The value is given to us in the question, it's not something we found, it's a given. If you labeled it "a, b, c, cp, cv" makes no difference. The specific heat value was given. In real life, the pressure that increases in oil with a small temperature difference as stated in the question is negligible. But that is beside the point, there is a difference between cp and cv values, but in this question, this value was given to us, so the "label" doesn't matter. :)
It should have been labeled cv, but that value was given in the question. So it's a typo on my part. Also, oil is an incompressible substance so you can interchange cp and cv.
So generally speaking, if the volume doesn't change, you can use cv, and if pressure doesn't change, you can use cp. So in the argon problem, the pressure changes by a large degree, so cp can't be used.@@H5EVER
No, so if you listen again at 8:16, I said, we are going by the normal convection, which is simply to assume that work is done ON the system. We have no idea what's happening, it's just an assumption until we get our answer. I hope that makes sense 👍
Why did you assume the ambient pressure was 100kPa. Was it because they said it was happening in a room, so you assumed it was at atmospheric pressure(101,3kPa) but just rounded to 100kPA?
For the second question, why are we using Cv to calculate the change in internal energy when the process is clearly NOT a constant-volume process? Isn't Cv the specific heat at constant volume?
There are only two options to use, either Cp values or Cv values. Here, the initial pressure is 120 kPa, and final pressure is 800 kPa. The difference is far too great to use a Cp value and our results would create a large margin of error. So Cv has to be used. In addition, keep in mind that pressure increasing generally indicates a constant volume process.
Even though I have nothing to do with this topic , I just got a notification about it all I wanna say is that It's been a year since this guy gave me an A+ in dynamics .
I am still very thankful to you .❤️🌹
Thank you very much for taking the time to comment. Plus, very nice on getting an A+ on your dynamics course. Keep up the awesome work :)
❤❤❤❤❤,How is it possible for a man to have such knowledge which is divergent.Thank u Demigod
You are too kind! ❤❤
For the question at 6:00
Why did we use Cp for oil and Cv for air? Well for air it's understandable since it's in a fixed volume of 50 cubic metres, but the oil is in that fixed volume of the heater as well, right? Why is the volume then considered to be changing here?
Actually, it doesn't matter, since the value was given, whether it's cv or cp. You can make cp to be cv, and assume it to be a constant volume as well. It really only matters if you have to look up a value in a table. 👍
For the room, your statement is correct, it is a fixed volume since there are no air leaks, which is why we looked for the cv value.
@@QuestionSolutions "if it's close enough, it works" lmao
Thanks for the clarification!
@@akshatverma3529 No, that's not what I said at all. The value is given to us in the question, it's not something we found, it's a given. If you labeled it "a, b, c, cp, cv" makes no difference. The specific heat value was given. In real life, the pressure that increases in oil with a small temperature difference as stated in the question is negligible. But that is beside the point, there is a difference between cp and cv values, but in this question, this value was given to us, so the "label" doesn't matter. :)
@@QuestionSolutions OHHHH alright thanks again!! ^-^
@@akshatverma3529 :)
Why did u use cv for air & cp for oil in the first question?
Thank u
It should have been labeled cv, but that value was given in the question. So it's a typo on my part. Also, oil is an incompressible substance so you can interchange cp and cv.
Why did u use q-w = delta u for comprehension in the second question?
Thank u
Please give me a timestamp so I can take a look at the spot you're referring to. Thanks!
your videos have been amazing for me, thank you so much!
I am happy to hear that. You are very welcome and keep up the good work!
In 6:27 How can we understand that we have to assume ideal gas law for air? I cant understand when have to use ideal gas law.
Please see this video first: th-cam.com/video/Wmewd-vv12Y/w-d-xo.html
How can one understand that should i take cv or cp e.g you took the cv for argon , how can i know which one should i take
Am i right
Cv=when body is well sealed (like for air in 1st problem)
But Cp = ?
So generally speaking, if the volume doesn't change, you can use cv, and if pressure doesn't change, you can use cp. So in the argon problem, the pressure changes by a large degree, so cp can't be used.@@H5EVER
@@QuestionSolutionsooh okay 👌
Very informative :)
Thank you :)
At 8:29, you said "work is done ON the system..." but I am pretty sure you meant to say 'work is done BY the system...', right?
No, so if you listen again at 8:16, I said, we are going by the normal convection, which is simply to assume that work is done ON the system. We have no idea what's happening, it's just an assumption until we get our answer. I hope that makes sense 👍
Why did you assume the ambient pressure was 100kPa. Was it because they said it was happening in a room, so you assumed it was at atmospheric pressure(101,3kPa) but just rounded to 100kPA?
Please give me a timestamp so I know where you're referring to. Then I can help you out better. Thanks!
For the second question, why are we using Cv to calculate the change in internal energy when the process is clearly NOT a constant-volume process? Isn't Cv the specific heat at constant volume?
There are only two options to use, either Cp values or Cv values. Here, the initial pressure is 120 kPa, and final pressure is 800 kPa. The difference is far too great to use a Cp value and our results would create a large margin of error. So Cv has to be used. In addition, keep in mind that pressure increasing generally indicates a constant volume process.