Physics 29 Efficiency Of Heat Engines (13 of 14) The Carnot Cycle

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In this video I will explain and develop the efficiency equations of the Carnot cycle.

[@physicsexplainedsimply114]

Michel you are honestly the greatest teacher I have ever had and I dont even know you, thank you so much for these videos I genuinely would be in a massive pickle otherwise. I wish you all the best

[@MichelvanBiezen]

Thank you. Glad you find our videos helpful.

[@anusharma6090]

Why aren't you my physics teacher??!! You are too good at explanation

[@bios546]

WOOOOOOOOOOOOAAAAAAAAAAAAAAAAAAAAAAAWWWWWWWWWWWWW... my greatest doubts... are clarified!! thanks to u sir!!!

[@XplosiveAction]

If we are looking at the absolute value in the end, of the quantity QC/QH, are you essentially saying that we can calculate QC and QH using the initial equations, and just saying "we know that the magnitude of each values are representing simply how much heat is added or removed" its kind of like, the negative sign is saying that too

[@salliet9653]

thank you sir. your lectures have really helped me. I didn't get why you took the absolute value for Qc/Qd.

[@MichelvanBiezen]

Because we only wanted the ratio, in order to find the efficiency. (Positive Q = heat ADDED to the gas, negative Q = heat REMOVED from the gas)

[@biancapena1355]

Dr. Biezen, you have saved me in my Engineering Physics I and II classes, and now for Thermo. Thank you for your work! You broke down the concepts of the Second Law perfectly! I haven't struggled on my homework. :)

[@MichelvanBiezen]

Thank you for your comment. It is good to know that our videos are helping students around the world. :)

[@rameshdas7788]

Thank you very much...

[@g7sky]

thanx for making this video ! this is the one

[@allenmolina1269]

Hi Sir... Why Qc is positive even if Va is larger than Vb. When we take the natural log of that Vb/VA we'll get a negative sign. Vice versa with Qh... Thank you for all the knowledge

[@nthumara6288]

can not we replace t insted of q when finding efficincy in pravtical engine

[@MichelvanBiezen]

We use T (temperature) for theoretical engines like the Carnot engine. For real engines we need to use the actual heat exchanged, Q

[@samexcelll123]

Thank you Sir

[@MichelvanBiezen]

Most welcome 🙂

[@historyisthebest5831]

Professor, can you please make a few videos on practicing how to read PV diagrams fast? I don't think I'm proficient enough in reading and analyzing PV diagrams.

[@MichelvanBiezen]

My suggestion is to go through each of the videos on the first law of thermodynamics and all of the videos on the various thermodynamic processes as well as the videos on PV = nRT. After that you'll have a full understanding of the PV diagram. (That is why we made all of those videos)

[@historyisthebest5831]

Is Qh suppose to be entering during path AB and not CD?

[@andreapaulsen3006]

I'm sorry to say that your argument for only looking at the quantity not the sign is somewhat unclear. Qc is negative as you write it - because of ln(Vb/Va). Instead you should write e=W/Qh=(Qh+Qc)/Qh=1+Qc/Qh and then argue written with numerical notation e=1-|Qc|/|Qh| because 01. But that's just my humble opinion.

[@historyisthebest5831]

Actually the efficiency is e = Qh - Qc / Qh

[@venkateshreddy3519]

best one

[@drayushjain_]

Excellent.

[@shaherbano1334]

Sir, why Temperature is discussed in Carnot Engine or Carnot Cycle instead of Heat Q as in real engine???

[@MichelvanBiezen]

The Carnot engine is NOT a real engine. It is just a theoretical engine, that shows the maximum theoretical efficiency. A real engine can never reach of exceed this efficiency, and it depends on the operating temperatures.

[@shaherbano1334]

Thanks Sir.

[@fozymilograno]

very good!

[@naqeefhatta7782]

Hi Sir, I really like your videos. Do you mind going through Brayton cycle?

[@MichelvanBiezen]

That will have to wait. Working on too many other topics right now.

[@somaabdallah7917]

please I would a course of carnot of non-reflective?!

[@starwarsedison]

very clear

[@tsoojbaterdene7793]

We invented refrigerator.And It was nature law-breaking invention.

[@MichelvanBiezen]

Yes, it is like making water flow up hill. It requires work.

[@mizpahobcial8655]

where did the nRT and In came from?

[@MichelvanBiezen]

PV = nRT

[@annasarahkramerfazendeiro8030]

Why are we allowed to take the absolute value of QH/QC in the end of the video?

[@MichelvanBiezen]

Because the ratio of Tc/Th can never be negative

[@md.mominulislam5068]

Sir, how you cancel out the natural logarithms ? It is not clear yet.

[@MichelvanBiezen]

+Md. Mominul Islam Because Vb/Va = Vc/Vd

[@MohammadkazimHalimy]

Video quality is so bad😢

[@MichelvanBiezen]

Yes indeed. We had a lot to learn when we started filming these videos.

[@AlaaMohamed-ct5jt]

why did you take the absolute value ?!!

[@MichelvanBiezen]

+alaa ashraf Q is positive when added TO the gas and Q is negative when removed FROM the gas. Thus the ratio of Qc to Qh can be positive or negative and the temperature can only be positive.

[@AlaaMohamed-ct5jt]

Michel van Biezen the work total in Carnot cycle does it equal qin plus or minus q out ?? What the right rule is not plus or minus Because there are argue about that between people Can I have your email , because I have abother question concerning thermodynamics

[@MichelvanBiezen]

+alaa ashraf The work done in any cycle equals the net inflow of heat (Q), since the change in internal energy is zero for any cycle. The sign for q only depends on how you define the first law of thermodynamics. (Look at the video on the first law of thermodynamics. )

[@AlaaMohamed-ct5jt]

Michel van Biezen can I have your email ?

[@satyamkumar567]

Video quality is very poor

[@MichelvanBiezen]

Apologies...When we first started our KZbin educational channel, we had ABSOLUTELY NONE, ZERO experience in video-making. We were math/physics not film-making majors. So we had absolutely zero clue about lighting and sound. Fortunately we do have a learning curve. So our “less old” videos have better lighting, focus, and sound.

[@ajavier38]

@@MichelvanBiezen It's still a great and helpful video!