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No the second law of thermodynamics Why making a mis

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is just part of physics into chaos Cleaning doesn't violate

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the laws of physics But your parents The key to

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a happy life is to make sure everything is in

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its place But you spend most of your waking life

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making sure things are organized and properly stored The rest

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of your life will be so much happier and sure

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you could take this advice too far Theoretically But we

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have to do everything we can to fight disorder because

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the universe is fighting back against us Stupid messy universe

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What does a clean bedroom have to be with physics

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to answer that question let's talk about thermodynamics The first

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law of thermodynamics says that energy can't be destroyed or

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created All the energy in the universe already exists It's

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not going anywhere And no new energy is going toe

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walk through the front door The second law of thermodynamics

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actually has a few different definitions or different ways We

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can understand it Have you ever dropped a few ice

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cubes in a glass of soda and then forgot it

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on the counter I haven't But let's assume you have

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when you come back It's a gross water down disaster

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What happened Heat transfer happened That's what heat moves from

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the warmer soda into the colder ice Cubes making them

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melt so why didn't it work the other way around

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Why didn't the heat go from the ice cubes of

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the soda Sure the ice cubes are super cold but

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they still have internal energy but it would be pretty

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freaky if you put ice and soda and the ice

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somehow got colder and yeah turns out that never happens

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It's actually impossible it would break the second law of

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thermodynamics One way to explain the second law is to

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say that he'd always flows from a higher temperature system

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to a lower temperature system and it never ever goes

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the other way around That just makes sense it's one

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of those things that's so obvious you wonder why they

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even had to write it down I'm not judging but

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it turned out that the second law is a little

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more complicated than that because the second law of thermodynamics

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is really about entropy which is a fancy science word

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for disorder or chaos The best definition of the second

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law of thermodynamics is as follows in all natural processes

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The total entropy of a system and its surrounding environment

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either stays the same or increases entropy Never decreases To

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put that a normal person speak things always become more

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disorderly if we consider both the system and the environment

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around them Let's say it's a wonderful day for fun

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and we get to spend eight hours organizing the house

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It doesn't get any better than that does it Just

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a full day of organizing and tiding by the time

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you're done it's almost as if you can't detect any

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sign of human life at all It's perfect it's Wonderful

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it's Sorry What was i saying Oh right entropy So

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we just showed that there can be less disorder in

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the universe At least here in our little pocket of

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it Right Sorry But now first of all any time

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you have that much fun you're going to work up

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a sweat That means heat came off of you and

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went into the air And when you heat molecules up

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they move around and vibrate and just get all worked

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up which means they get more chaotic and as you

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scurry around putting things away had also disturbs molecules in

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the air opening and closing dresser drawers putting things on

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hangers The joyful act of throwing junk Away all of

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that involves friction which means heat which means chaos There

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is no escaping it it's enough to drive you crazy

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but we don't get crazy because crazy is chaos and

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chaos is the enemy keep calm and clean on another

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example of this happens when we have a bouncy ball

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We've all played with one of these super balls that

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bounce like crazy right If you drop a super ball

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without adding any extra energy to it it'll bounce back

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up pretty high but it won't bounce all the way

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back up to where it started Part of that is

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due to gravity Part of that is also due to

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entropy right before the ball hits the ground It's got

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a lot of kinetic energy as it hit the ball

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do forms a little creating elastic potential energy Then it

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snaps back into its original shape which is why it

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bounces back up into the air The ground also deformed

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a little bit too And all of this d formation

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makes the molecules all jumpy So some of the kinetic

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energy of the ball is transferred into internal energy of

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the ball and the ground internal energy Means ah higher

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temperature And in fact if you had some thermometer keeping

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track of the super ball you'd see it tick up

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just a little bit like one or two tenths of

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a degree Maybe the ground's temperature would go up a

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teeny bit too Since some of the kinetic energy is

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converted into internal energy the ball loses some goof on

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its bounce and you guessed it more chaos is created

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There's just no way around it Okay Circling back How

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is entropy related to our first explanation of this thermodynamics

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law Remember we said that heat flows from the warmer

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system to the cooler system Think of it like this

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which is more orderly A block of ice or a

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bowl of water It's the ice without a question Molecules

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and a solid are tightly aligned there's no molecular slipping

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and sliding like you havin a liquid and in general

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a colder system has less chaos than a warmer one

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The molecules are moving more slowly they're vibrating less their

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little molecular shoes air neatly stacked up Ah hot system

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means chaos galore Molecules banging into each other electrons flying

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around willy nilly shoes never being put Away oh it

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makes me it's just thinking about it Entropy will always

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increase or stay the same If heat float out of

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a cooler system and into a warmer system that would

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mean the colder system would become more orderly That's never

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going to happen Another way to think about the second

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law of thermodynamics is toe pop the hood on your

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car assuming you don't have an all electric car than

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your engine has pistons which means it depends on heat

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which makes it well a heat engine and an internal

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combustion engine just like the one in this car has

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pistons A piston basically hangs out in a hollow cylinder

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at the top of the cylinder The piston is like

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a plunger that creates a tight seal to keep all

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the air inside So we've got gas inside the pittston

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just hanging out doing it gas thing when suddenly a

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heat source appears This makes the molecules in the gas

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get excited and less dense which creates pressure in the

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piston which pushes the piston up which makes the gears

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of the engine turn which makes the wheels turn And

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what do you now you're driving on The highway at

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a sensible speed of course five miles under the speed

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limit is best Okay so the gas expands greatjob gas

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But if this process happens only once that's not going

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to get you very far things have to cool down

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so the piston khun sink back down and the whole

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process can repeat it in a car This happens hundreds

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of times a minute Where does that heat go Bingo

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Out of the tailpipe any kind of heat engine has

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to be able to dump heat into what's called a

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reservoir In this case reservoir doesn't mean a big lake

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full of drinking water It means something big enough to

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be able to absorb all the heat that the engine

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needs to get rid of In the case of a

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car that means the heat goes through the tailpipe and

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out into the atmosphere The atmosphere is big enough that

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heat from a car doesn't have much effect on the

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overall temperature Of course when you have a bunch of

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cars with a bunch of pollution and greenhouse gases well

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that's a topic for another much more depressing video With

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the pistons going up and down we know that force

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is being applied and things are moving which means work

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is being done but since all the heat that's generated

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is dumped into the exhaust system this process isn't one

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hundred percent efficient And that brings us up to our

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third and final way of looking at the second law

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of thermodynamics It's impossible for a heat engine to convert

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heat completely into work without any other effect In fact

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there's a nice and clean equation to go along with

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this idea the efficiency of a heat engine that's what

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the epsilon stands for equals the work done w divided

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by the heat that's input that's the cue sub h

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because he can't be totally converted into work work will

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always be less than the heat input and efficiency will

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always be less than one Not everything in life is

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about cars you know no matter what you're one uncle

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who's obsessed with hot rods might say here's a basic

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diagram of how another type of heat engine works We've

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got a high temperature reservoir on the one end that

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feeds into the engine which partially converts the heat toe

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work Then it sends the excess heat That wasn't converted

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down the line to the low temperature reservoir let's say

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this engine does five thousand jewels of work while producing

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nine thousand jewels of heat what's the efficiency of this

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bad boy we just went over the equation for heat

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engine efficiency but let's make sure we know how to

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actually use it There has to be a difference in

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temperature from the heat source to the cold reservoir otherwise

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heat wouldn't flow and that would leave us with an

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engine that date a whole lot of nothing Or maybe

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something worse than nothing kind of defeats the whole purpose

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of an engine And according to our thermodynamic lawyer the

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engine doesn't convert all of the heat into work so

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what's leftover has to exit the system So we've basically

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got two different kinds of heat here We've got the

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heat that enters the system we call that que ce

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of h then we've got the heat that leaves the

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system will make that cues up L so what do

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we know in this situation For one thing we know

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that the heat engine produces nine thousand jewels of heat

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Is that the heat coming into the engine or leaving

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the engine That would be our new friend q Sub

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l since the engine is producing it and not taking

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it in this nine thousand jewels is what the engine

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is dumping into the reservoir And then we've got our

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five thousand jewels of work Of course our efficiency equation

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tells us that a heat engines efficiency equals the work

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produced over the heat entering the engine We still don't

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know how much heat is coming in but it's not

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too tricky to figure out After all we know that

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an engine is going to produce two things work that's

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been converted from heat and heat not converted to work

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So if we add these together we've got our starting

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heat which means that we can rewrite our efficiency equation

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by swapping out the heat coming into the engine for

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the heat leaving the engine plus the work done Now

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we just have to pop in our numbers and we're

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all good Five thousand jewels divided by fourteen thousand jewels

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gives us an efficiency of thirty five point seven percent

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which isn't great I certainly hold myself to a higher

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standard than that but that's the way It goes with

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heat engines they're just not that great with the whole

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efficiency thing Now let's say we've got an engine that

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takes in sixty four thousand five hundred jewels of heat

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and gives up fifty three thousand nine hundred jewels and

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exhaust what's our efficiency here are equation uses work and

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the heat input to figure this out but we don't

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have work here That's okay though we can tackle this

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in two different ways First we confined the work by

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subtracting the heat leaving from the heat entering that tells

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us how much heat was converted into work In this

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case that comes to ten thousand six hundred jewels divide

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that by good old cues up h and we've got

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an efficiency of sixteen point four percent The other way

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to figure this out is to start with one If

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an engine was one hundred percent efficient the work would

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equal the heat coming in so this ratio would equal

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one From that we can subtract the result of the

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heat leaving the system divided by the heat coming in

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So one minus fifty three thousand nine hundred jewels over

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sixty four thousand five hundred jewels gives us sixteen point

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four percent efficiency See like the old saying goes there's

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more than one way to clean the stove And of

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course we always need to remember that as a result

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of all this inefficiency and he dumping more entropy is

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introduced into the universe There's no getting away from that

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which is why i hate this stupid second law Why

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can't we just make things more easily Wouldn't that make

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the universe a better place No one actually likes chaos

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do they Everything moving around going crazy no one and

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forcing any rules people just doing whatever they want eating

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whatever they want not caring about anything Tacos in the

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street there are toilets to be clean young man Sometimes

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i swear i'm the only one who cares about order 00:11:18.893 --> [endTime] in the universe

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