We made quiz questions to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: apple.co/3d4eyZo Download it here for Android Devices: bit.ly/3TW06aP
That diagram at 1:42 is almost exactly how your house gets electricity (unless your grid is fed by solar or wind). The power plant uses coal, natural gas, oil, nuclear fission or even garbage to create heat in what they show as the boiler. Then just replace that piston with a steam driven turbine that turns a big generator and boom, your house has glorious power.
Which mathematics? There are so many fields. Arithmetic, Algebra, Geometry, Trigonometry, Calculus, Statistics, Set Theory, Topology, Real/Complex Analysis, etc...
Maybe a General Math applicable too all fields... cause every profession needs at least one math field or branch or a few.......and students in secondary schools need all of them in basic....and math majors need all of the branches in advanced. :)
Thanks! The production value is great. However: At 05:00 you say that there is an isothermal process where heat is slowly added, but the animation shows lots of heat (Q_H) escaping. What gives? At 05:04 You say that the isothermal expansion is 1/2 AB. Shouldn't it be the *entire* path AB? At 05:15 you say "the temperature drops whilst the heat stays constant, which also makes the volume expand". Well this is misleading: a temperature drop would cause an isolated system volume to contract. However in a Carnot engine, the system is doing work on the atmosphere, converting internal energy into work, and dropping the temperature. It's best to say that the expansion work drops the temperature, not that a colder temperature causes an expansion. Also, when you keep saying "the heat stays constant", shouldn't you be saying "there is no heat flow" or something equivalent? At 05:40 you say "the heat doesn't change" but perhaps you should be saying that there is no heat flow, or the system is thermally insulated, or something else equivalent. The way you explain it sounds as if heat is a state property, when it's not.
Excellent video on engines! I'm really looking forward toward our next segment of the course: Electricity and Magnetism! Time to explore Electric Potential and Gauss' Law!
before my summer vacation they were exactly sincronised with what i did at school. in the vacation they we don't do, so it's perfectly sincronized now too :)) helps me a lot, as this year we have a bad teacher
I spent an hour this morning reading about thermodynamic engines from a Physics textbook and still had trouble understanding. Then I watch this 10 minute video and immediately understand what's going on.
Compilation Guy>>>> And I need a crash course on basic gymnastics and acrobatics that covers front- and backhandspring, front and back somersault, aerial, side-somersault and handstand.
Failure is always a option. To say that it isn't one is an illusion. The trick is to avoid failure. If one runs into a failure state, learn from it to increase the chances of success.
I'm doing a degree in physics. We have t covered this yet and I find this confusing. I really only think people enjoy watching these videos if they already understand the topic. I don't think that crash course's style is at all suited to physics
pro tip to watching these fast videos: pause between sentences to mimic a realistic conversation and time for your brain to understand what she just said.
The animation of a refrigerator at work is completely reversed and incorrect: after the liquid is turned into a gas it is compressed at which point it flows to the condenser to shed the heat extracted in the fridge(and the heat generated by being compressed) and return to a liquid. This liquid is then sent through an orifice or long, thin capillary tube so that it pressure is reduced hence it's temperature lowered. This liquid then goes to the evaporator inside the fridge where it absorbs heat from the interior and boils into a gas before returning to the compressor. The animation shows the compressor as a "decompressor" or expansion device(orifice, capillary tube) and that is opposite of it's true function as the whole thing is reversed.
A nice recap for those that understand the principles already but far too quick for new comers. Was hoping to use this in a lesson on the Otto cycle but it's above and beyond my year 13 pupils!
Is there a quantity to describe how well a real engine compares to a Carnot engine working across the same temperature range. Like actual efficiency/Carnot efficiency
Where would electric engines stand? They start off with ambient heat, max torque at 0rpms, output heat is significantly lower than a steam or an IC engine, practically all are reversible. (Edited to fix auto correct errors)
Electric engines convert electromagnetic energy into kinetic energy. It's an entirely different process. In principle, an electric engine is the same as a generator, but used in reverse. If you spin it, it produces an alternating current. If you give it some AC, it will try to spin fast enough to match the frequency of the current.
I found a little bit confusing the explanation about the reason of isothermal processes in carnot cycle.. It's isothermal to favor reversibility?? It does not make too much sense, because the heat transfer is with the hot source and cold sink not within the cycle... I mean there is indeed a temperature difference between the hot source and the hot isothermal process, the only fact that maintain the process isothermal is that it's doing work at the same time that it absorbs heat... Other remark is that the T-s diagram is more apropiate to understand heat engines cycles and it efficiencies (just need to spot the ratio between the area under the cold curve and the area under the hot curve)
I don't think this series has really explained entropy well enough for a T-s diagram to be helpful to anyone hearing about thermodynamics for the first time. As far as reversibility goes, isothermal and adiabatic processes are required, du to the definition of reversibility. Any heat transfer from a high temperature to a lower one produces entropy. A reversible process produces no entropy. If there is no temperature difference during the heat exchange, no entropy is produced, making isothermal processes the only reversible kind of process that allows for heat exchange, while adiabatic processes pass for reversible by not having any heat exchange that can produce entropy.
I don't think this series has really explained entropy well enough for a T-s diagram to be helpful to anyone hearing about thermodynamics for the first time. As far as reversibility goes, isothermal and adiabatic processes are required, du to the definition of reversibility. Any heat transfer from a high temperature to a lower one produces entropy. A reversible process produces no entropy. If there is no temperature difference during the heat exchange, no entropy is produced, making isothermal processes the only reversible kind of process that allows for heat exchange, while adiabatic processes pass for reversible by not having any heat exchange that can produce entropy.
You have stated a contradiction " A reversible process produces no entropy. "; the isothermal process of carnot engine DO produce entropy, you can easly check the T-s diagram or think in terms of dQ = TdS; for heat to be transferred you need to augment the entropy content.
Abraham Vivas Isothermal heat exchange leads to entropy being transferred, but no entropy is produced, in the ideal case. dQ = TdS only deals with entropy transfer in internally reversible processes. I'm not saying the entropy doesn't change in a reversible process, only that no new entropy is produced. Any entropy increase in a Carnot process is brought in with the added heat, and transferred back out again, when the system gets rid of heat.
Only with me or there was an issue with the mic in this video? There is a high-frequency "shhh" in her voice I never heard in any of the videos before o.O
That's probably a lot less efficient, since most nuclear plants are basically steam engines hooked up to generators. You wouldn't need an entire cart for fuel (instead, you would probably need several carts filled with cooling water to prevent a nuclear meltdown), but you would use the steam engine to get kinetic energy, to convert to electricity, only to convert it back into kinetic energy. Not that I want to break your steampunk bubble. It's just, if you want a nuclear powered train, skip the conversion into electricity.
A conventional RTG is probably not hot enough, a small fission reactor combined with a cryo cooling system, lot's of heat exchangers and a large water tank, point is that all the coal hassle is gone and a few grams of plutonium is gonna last forever with additional radiation issues i know ;-) A train still needs a lot of electrical power for other functions.
robson668 That's why you connect both the generator and the gear box to the axel coming out of the steam engine. Just make it do double the work. Plutonium should give you the energy you need :) Just don't waste energy and materials by using an electric motor (aka a second generator)
Off topic of the contents of the video ... sound editing seems a bit off, as her 'S' (or soft 'C') are very harsh and cutting, as if that frequency was amplified or something.
The heat engine doesn't care where the heat comes from. Radiation works too! And if you don't like splitting uranium (or other big atoms) to get radiation, there are solar plants that use sunlight to power steam engines.
I'm sure someone can figure out how to use Maxwell's Demon for a Carnot engine but I myself can only envision it in a long chain. I'm not sure how many would be needed, I would surmise at least 3 but that doesn't take into account human perception which occurs at ~ .02-.05 secs per frame. It may be a hundred for all I know.
No. A Carnot engine has nothing, directly, to do with Maxwell's demon. It is also important to point to point out that, as of Sept 22, 2016, Maxwell's demon remains a totally imaginary device. It was and is a thought experiment. Even as a thought experiment, it is generally considered that it could not violate the second law of thermodynamics, though the theoretical thinking involved is quite abstract. There have been practical devices built that have some characteristics of a Maxwell's demon, but none of these, either in theory or practice, violate the second law.
I think I should clarify what I mean by a "practical" device that has some characteristics of a Maxwell's demon. By practical, I mean a real device working with real atoms and molecules, not merely a theoretical construct. However, these devices are not practical in a larger sense. They are laboratory research devices. They allow research into interesting physics and chemistry. They will not power your lawnmower.
These videos are good overall, but that's just an awful description of how a refrigerator works. She doesn't even mention the pressure difference in the two halves of the loop. Also, all you young'uns with working high-pitch hearing need to learn how to use the equalizer on your computer or phone.
We made quiz questions to help you review the content in this episode! Find them on the free Crash Course App!
Download it here for Apple Devices: apple.co/3d4eyZo
Download it here for Android Devices: bit.ly/3TW06aP
I'm a mechanical engineer that's passed the thermal and fluid design PE exam, and i found this video helpful as a reminder of the basics! Thank you
Can I ask if you are circumcised or are interested in foreskin regeneration technology?
What a great teacher; that's a lot of thermodynamics in 10 minutes
and she is cute lol
Cool!
XD i'd let her give me a mustache ride
You might say she's highly efficient.
@7:25 i guess that's why it's called a "car no engine"
in this show, you have to listen to EVERYTHING
Yeah that too
That diagram at 1:42 is almost exactly how your house gets electricity (unless your grid is fed by solar or wind). The power plant uses coal, natural gas, oil, nuclear fission or even garbage to create heat in what they show as the boiler. Then just replace that piston with a steam driven turbine that turns a big generator and boom, your house has glorious power.
The graphics have a copy editing problem. Several times, including the first, Q sub H is captioned as "input temperature" not "input heat".
I really need a crash course mathematics...
Which mathematics? There are so many fields.
Arithmetic, Algebra, Geometry, Trigonometry, Calculus, Statistics, Set Theory, Topology, Real/Complex Analysis, etc...
for me, trigonometry, calculus, and statistics...
Math is math. A system that is composed of characters that have value & function. All "fields" of math is just a variation of this principle.
Maybe a General Math applicable too all fields... cause every profession needs at least one math field or branch or a few.......and students in secondary schools need all of them in basic....and math majors need all of the branches in advanced. :)
I am Successful
Arithmetic is boring.
This makes a hundred times more sense than my thermo textbook. Stay awesome Shini!
PLEASE make CrashCourse Algebra/Geometry/Calculus.
Crash Course Math.
+Ricardo Mazeto too general
I really like that y'all have the Giancoli book. I mean, idk if y'all use it but it was my favorite physics book and I feel an extra connection now.
7:42 The Little Engine That Carnot. Ha!
Nice job explaining the Carnot engine; better than my own lecturer did.
I could listen to you whole day.
Thanks! The production value is great. However:
At 05:00 you say that there is an isothermal process where heat is slowly added, but the animation shows lots of heat (Q_H) escaping. What gives?
At 05:04 You say that the isothermal expansion is 1/2 AB. Shouldn't it be the *entire* path AB?
At 05:15 you say "the temperature drops whilst the heat stays constant, which also makes the volume expand". Well this is misleading: a temperature drop would cause an isolated system volume to contract. However in a Carnot engine, the system is doing work on the atmosphere, converting internal energy into work, and dropping the temperature. It's best to say that the expansion work drops the temperature, not that a colder temperature causes an expansion.
Also, when you keep saying "the heat stays constant", shouldn't you be saying "there is no heat flow" or something equivalent?
At 05:40 you say "the heat doesn't change" but perhaps you should be saying that there is no heat flow, or the system is thermally insulated, or something else equivalent.
The way you explain it sounds as if heat is a state property, when it's not.
Excellent video on engines! I'm really looking forward toward our next segment of the course: Electricity and Magnetism! Time to explore Electric Potential and Gauss' Law!
I love Gaussian curvature, is it the same Gauss? Must be. I'mma look that up. Thanks! ;)
If you're looking for electricity videos I have some you might want to check out :) Just click my channel link and they're on the front page!
This was very helpful, thank you
before my summer vacation they were exactly sincronised with what i did at school. in the vacation they we don't do, so it's perfectly sincronized now too :)) helps me a lot, as this year we have a bad teacher
I mean your videos are of such a high quality this is how we should learn in schools
this is where we left off in our first year at uni XD and I start in a few days! Perfect timing if I do say so myself!
I spent an hour this morning reading about thermodynamic engines from a Physics textbook and still had trouble understanding. Then I watch this 10 minute video and immediately understand what's going on.
Fantastic!
Compilation Guy>>>> And I need a crash course on basic gymnastics and acrobatics that covers front- and backhandspring, front and back somersault, aerial, side-somersault and handstand.
yes very nice
a great teacher
Good summary of information covered in many Crash Course Engineering videos. They're all awesome. Thanks! :)
Thanks for sharing this!
love.
Shini, do you play Magic The Gathering? The new set, Kaladesh, is about invention and is inspired by India. I have a sense you will really like it.
That's great! I love this series
Just! a crash course for automobiles would be phenomenal... (With a long silent please)
Brilliant... plz tell me which software have u used to create these animations... i shall be highly Grateful
Heat engines and refrigeration. Called it!!
So good my professor can teach RUclips is my saver now for physics 2 . Sadly
I dig the Failure is Not an Option book on the desk
Failure is always a option. To say that it isn't one is an illusion. The trick is to avoid failure. If one runs into a failure state, learn from it to increase the chances of success.
Tell that to Gene Kranz
MrPyrolemon The dice rolled in his favor.
Thanks to you i will pass physics 2
I will watch any crash course she teaches
A small part of me thought this was going to be about rocket engines and I got really excited.
Same underlying concept, just more complex and different details.
What makes a rocket a rocket is that it carries it's oxidizer with it instead of using ambient air
***** They don't use any of the systems shown in the video in particular though. Way more simple, just more plumbing.
the biggest game changer in human technology was the transistor
Can anyone make a summary for this video please, i really need them for an assignment
this IS the summary
The sound engineer needs to fix the s's.
ssssssay what?
They have a sound engineer? All I heard was echos.
They just need to put a De-Esser on the audio track.
you know, if you think about it you could in Theory build a stream powered refrigerator
Crash course sociology please!
They're looking for a teacher
The last time i was this early, the hospital had to put me in an incubator
Coooooooooooler
I'm doing a degree in physics. We have t covered this yet and I find this confusing. I really only think people enjoy watching these videos if they already understand the topic. I don't think that crash course's style is at all suited to physics
pro tip to watching these fast videos: pause between sentences to mimic a realistic conversation and time for your brain to understand what she just said.
I have a question guys... if QH=R*TH*ln(V2/V1) how do we find those volumes?
oh god that giancoli book in the background gives me bad memories
The animation of a refrigerator at work is completely reversed and incorrect: after the liquid is turned into a gas it is compressed at which point it flows to the condenser to shed the heat extracted in the fridge(and the heat generated by being compressed) and return to a liquid. This liquid is then sent through an orifice or long, thin capillary tube so that it pressure is reduced hence it's temperature lowered. This liquid then goes to the evaporator inside the fridge where it absorbs heat from the interior and boils into a gas before returning to the compressor. The animation shows the compressor as a "decompressor" or expansion device(orifice, capillary tube) and that is opposite of it's true function as the whole thing is reversed.
She speaks so quickly, and like from a script...
sorry, didnt wait till the end. I checked the description... none of the info there. got the host in the credits, ill do the research
Sergio Furtado has
I want to see her in a Quiz Show
What came first steam engines or steam heating?
A nice recap for those that understand the principles already but far too quick for new comers. Was hoping to use this in a lesson on the Otto cycle but it's above and beyond my year 13 pupils!
Yeah, we totally wouldn't be doing this (whatever it is you're doing right now) without the industrial revolution.
And without Capitalism... 😃
Is there a quantity to describe how well a real engine compares to a Carnot engine working across the same temperature range. Like actual efficiency/Carnot efficiency
Just wondering,is the 4 stages of the Carnot cycle somehow related with both the diesel and petrol engine compression and combustion cycles?
I couldn't find this video in the physics playlist
This chick is hot and smart I enjoy listening to her voice it makes learning more captivating.
I could listen to this woman speak for days..
Where would electric engines stand? They start off with ambient heat, max torque at 0rpms, output heat is significantly lower than a steam or an IC engine, practically all are reversible.
(Edited to fix auto correct errors)
I'm no expert, but there must be a very low input temperature, as electrons don't have one.
An electric motor is not a heat engine so this course segment does not cover how the motor converts potential energy into work.
Electric engines convert electromagnetic energy into kinetic energy. It's an entirely different process.
In principle, an electric engine is the same as a generator, but used in reverse. If you spin it, it produces an alternating current. If you give it some AC, it will try to spin fast enough to match the frequency of the current.
COOOL!
So COP is the same as efficiency?
I want hank :(
That's what I thought to when I read this chapter. Between the vinsmoke and he clones.
my three month class squeeze into 10min
The audio could do with a de-esser, or is it just me?
No mention of the creators of the steam engine?
7:42 That face tho
watch this at 0.75 speed if you want her to speak at the pace of a normal human
At 2:24, is that boat going backward?
whos this host? are they engineers or scientists? aero/fluid-dynamics
I found a little bit confusing the explanation about the reason of isothermal processes in carnot cycle.. It's isothermal to favor reversibility?? It does not make too much sense, because the heat transfer is with the hot source and cold sink not within the cycle... I mean there is indeed a temperature difference between the hot source and the hot isothermal process, the only fact that maintain the process isothermal is that it's doing work at the same time that it absorbs heat... Other remark is that the T-s diagram is more apropiate to understand heat engines cycles and it efficiencies (just need to spot the ratio between the area under the cold curve and the area under the hot curve)
I don't think this series has really explained entropy well enough for a T-s diagram to be helpful to anyone hearing about thermodynamics for the first time.
As far as reversibility goes, isothermal and adiabatic processes are required, du to the definition of reversibility.
Any heat transfer from a high temperature to a lower one produces entropy. A reversible process produces no entropy. If there is no temperature difference during the heat exchange, no entropy is produced, making isothermal processes the only reversible kind of process that allows for heat exchange, while adiabatic processes pass for reversible by not having any heat exchange that can produce entropy.
I don't think this series has really explained entropy well enough for a T-s diagram to be helpful to anyone hearing about thermodynamics for the first time.
As far as reversibility goes, isothermal and adiabatic processes are required, du to the definition of reversibility.
Any heat transfer from a high temperature to a lower one produces entropy. A reversible process produces no entropy. If there is no temperature difference during the heat exchange, no entropy is produced, making isothermal processes the only reversible kind of process that allows for heat exchange, while adiabatic processes pass for reversible by not having any heat exchange that can produce entropy.
You have stated a contradiction " A reversible process produces no entropy. "; the isothermal process of carnot engine DO produce entropy, you can easly check the T-s diagram or think in terms of dQ = TdS; for heat to be transferred you need to augment the entropy content.
An isentropic (no entropy change) process is adiabatic (no heat transfer) by definition.
Abraham Vivas Isothermal heat exchange leads to entropy being transferred, but no entropy is produced, in the ideal case.
dQ = TdS only deals with entropy transfer in internally reversible processes. I'm not saying the entropy doesn't change in a reversible process, only that no new entropy is produced. Any entropy increase in a Carnot process is brought in with the added heat, and transferred back out again, when the system gets rid of heat.
0.75 speed is prime
Hi
can you explain gyrscopic forces en where they come from?
anyone else completely lost by what she just said
I like trains
I feel that even though she's speaking very fast I can still hear that she has a accent, like she is British or something
I would have thought that this lady would have an accent more similar to the telephone operator from the movie "Transformer"
it is regular english received pronunciation
hello
WHY DOES THE ADIABETIC EXPANSION OR COMPRESSION OCCURS HERE?
Only with me or there was an issue with the mic in this video? There is a high-frequency "shhh" in her voice I never heard in any of the videos before o.O
No sound absorbency panels. Makes her talk like she's in a cave or in a restroom stall.
ap physics 2 exam in half an hour :D
Wonder if you could replace a steam train coal kettle by a radio isotope thermo-electrical generator, new age steampunk stuff ;-)
That's probably a lot less efficient, since most nuclear plants are basically steam engines hooked up to generators. You wouldn't need an entire cart for fuel (instead, you would probably need several carts filled with cooling water to prevent a nuclear meltdown), but you would use the steam engine to get kinetic energy, to convert to electricity, only to convert it back into kinetic energy.
Not that I want to break your steampunk bubble. It's just, if you want a nuclear powered train, skip the conversion into electricity.
A conventional RTG is probably not hot enough, a small fission reactor combined with a cryo cooling system, lot's of heat exchangers and a large water tank, point is that all the coal hassle is gone and a few grams of plutonium is gonna last forever with additional radiation issues i know ;-)
A train still needs a lot of electrical power for other functions.
robson668 That's why you connect both the generator and the gear box to the axel coming out of the steam engine. Just make it do double the work. Plutonium should give you the energy you need :)
Just don't waste energy and materials by using an electric motor (aka a second generator)
Swap the steam engine with a high efficiency Stirling engine or Quasiturbine for rotational conversion and we're on to something ;-)
Off topic of the contents of the video ... sound editing seems a bit off, as her 'S' (or soft 'C') are very harsh and cutting, as if that frequency was amplified or something.
you are nice loooking
Why is the audio so weird?
I thought it was only on my end. It's almost as if she talking in a cave. Is there no sound absorption foam in the studio she's in.
you sound lovely but it would be a lot better if you could slow down a bit. improved understanding!!!
Did the lights outline her body?
She talks really fast.
This beautiful physics is distracting me from studying this teacher. ;)
I thought they were going to talk about Box2d
steam engine coal pollution advance. Right. Half an advance maybe, but what about the environmental cost? More inventions were needed to combat that.
The heat engine doesn't care where the heat comes from. Radiation works too! And if you don't like splitting uranium (or other big atoms) to get radiation, there are solar plants that use sunlight to power steam engines.
So no car Carnot?
someone forgot to apply a de esser. having a hard time listening to this.
I think that this is ' to mathy ', show the engine first and then explain the principles and then do the math.
I'm a simple engineer
When I see girl do thermodynamics I love her.
Who is she???
Could a Carnot engine not be base on Maxwell's Demon?
I'm sure someone can figure out how to use Maxwell's Demon for a Carnot engine but I myself can only envision it in a long chain. I'm not sure how many would be needed, I would surmise at least 3 but that doesn't take into account human perception which occurs at ~ .02-.05 secs per frame. It may be a hundred for all I know.
After watching the full video, my money is still on Maxwell's Demon which has been created both mechanically and chemically.
No. A Carnot engine has nothing, directly, to do with Maxwell's demon. It is also important to point to point out that, as of Sept 22, 2016, Maxwell's demon remains a totally imaginary device. It was and is a thought experiment. Even as a thought experiment, it is generally considered that it could not violate the second law of thermodynamics, though the theoretical thinking involved is quite abstract. There have been practical devices built that have some characteristics of a Maxwell's demon, but none of these, either in theory or practice, violate the second law.
I think I should clarify what I mean by a "practical" device that has some characteristics of a Maxwell's demon. By practical, I mean a real device working with real atoms and molecules, not merely a theoretical construct. However, these devices are not practical in a larger sense. They are laboratory research devices. They allow research into interesting physics and chemistry. They will not power your lawnmower.
These videos are good overall, but that's just an awful description of how a refrigerator works. She doesn't even mention the pressure difference in the two halves of the loop.
Also, all you young'uns with working high-pitch hearing need to learn how to use the equalizer on your computer or phone.
u talking so fast :(