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You take fuel, rather you take something that's warm, and you put it in contact with the atmosphere, it cools down.
改变约束,继续加热,气体膨胀。
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All right, so I'm burning some energy, I'm burning some fuel to do this somehow, to get that work to happen.
而这个路径需要先加热再冷却，这样，我需要能量来源，比如燃料，来完成做功。
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The heater is on, it's producing heat until a negative signal is registered, 'oh we've gone too high', and then it turns off.
加热器会开着,一直产生热量直到它得到一个关闭的信号,噢我们弄得太热了,然后就关闭了
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And so as we add heat here, that was even quieter than last time.
因此我们在这里加热，怎么比刚才还安静啊？
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You know from experience if you've ever mixed them to make salad dressing, they don't mix too well. And you may know that if you heat them up, they mix much better.
经验告诉我们,你无法把它们混合做成色拉酱调料，他们不会很好的混合，但是你也知道,如果我们把他们加热，就能够混合的更好。
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That's the work that the system is doing to the environment. I'm doing work to the environment. The work is negative, which means that work is being done to the environment.
功的大小,就是矩形的面积,这样我们就实现了一台热机，冷却，加热，加热,冷却，系统回到了初态。
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W1 So I have my initial state, my final state, W1 my initial state, my final state here.
再加热，做功，对系统做的总功是。
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You've taken all the proteins inside the white of the egg, for example, you raise the temperature.
对蛋清部分所有的蛋白质,比如说进行加热
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Now to make that happen, it's not adiabatic, right. If I wanted to do that, I'd need a heating element or something to cool, so I could make that temperature change happen, right.
要实现这点，它就不会是绝热的，对吧，如果我想做到这点,我需要一个加热元件或什么制冷的东西,这样我才能让温度变化。
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You break the seal between them and feel the thing get cold, for example, right.
如果你买了制冷或加热包,你打开它们之间的封条。
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Here we have a fixed volume, and we have a little candle, and we're adding heat, and when we add heat, the pressure does what?
这里我们有一个容器，一个蜡烛，然后我们加热，这时压强会怎么变化？
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What you've built is an engine. You cool, you heat, you heat, you cool, you get back to the same place, but you've just done work to the environment.
这就是热机，我们用燃料或者热源加热，然后把它，与大气接触让它冷却。
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It works by a control mechanism called negative feedback, and the thermostat is measuring the temperature and then sending a signal to a heater somewhere.
是通过一种叫做负反馈的控制机制,探测器测量温度,再把信号传给加热器
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That great deal of specificity implies that heat is also path-dependent and again we have the convention that if heat is added to the system, the quantity is greater than zero.
热也是与路径有关的,根据通常的习惯,如果我们对系统加热，其符号取为正。
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In this case here, I heat and then I cool.
需要先冷却再加热。
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If the temperature drops below a certain level it sends a signal, 'turn on the heat', and that signal stays on until it gets a negative signal to turn off.
如果温度降到一定程度以下时,探测器会发送一个信号,打开加热器,直到加热器再收到关闭的信号,它就会一直开着
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We use a liquid helium. And so in order to make a liquid helium, you can't take helium at room temperature and do this, because if you did, you would just heat it up, because the room temperature is above the inversion temperature, so Joule-Thomson would heat up the helium.
为了得到液氦,不能再常温,做这个实验,否则就是加热氦气，因为室温高于它的转变温度,所以焦耳-汤姆孙，实验会加热氦气。
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You've just built a heat engine.
加热使压强增加。
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So I'm doing cooling and heating cycles.
需要怎么做？加热，对吧？
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It expands. You change your constraints on your system, you heat it up some more, then you take the heat source away, and you put it back in contact with the atmosphere. And you cool it a little bit, change the constraints, cool it a little bit more, and heat, and you've got a closed cycle engine.
让它与大气接触冷却,改变约束，使它继续冷却，然后又再次加热,这就是循环热机，我们以前也研究过，更复杂的机器。
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Or I could have a non-adiabatic, I could take the same temperature change, by taking a flame, or a heat source and heating up my substance. So, clearly q is going to depend on the path.
也能改变温度，绝热指的是没有热传递，在非绝热条件下，也同样可以升温,比如用火或者热源加热，这样，q也应当与路径有关。
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The native structure is this double stranded structure here and if I heat it up slightly and I add some base, so under slightly basic conditions, these molecules will fall apart because you've created conditions where the hydrogen bonding is no longer favorable so they peel apart.
原始结构,在这里就是指DNA双链,如果我稍微加热,并且加入一些碱,在弱碱性的条件下,这些配对碱基会分开,这是因为在一定条件下,碱基对之间的氢键,不再稳定并且会断裂分开
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If I had a beaker sitting on the table here and it contained a million blue double stranded DNA molecules and a million red double stranded DNA molecules and I heated it up and added a little base, I'd soon have four million individual strands just floating around in the solution because I've broken up this hydrogen bonding and the DNA molecules fall apart.
假如我这里有一个烧杯 里面,盛有一百万条蓝色DNA双链和,一百万条红色DNA双链,然后我稍微加热一下烧杯,并且加一些碱,很快我就有了四百万条DNA单链,漂浮在溶液里,因为我已经使得氢键断裂,DNA双链也随之打开
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Why does it mix better when you warm it up?
为什么加热之后混合变好了？
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We add heat to the system.
我们对系统加热。
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And so, we have this cartoon. Again, we have an open beaker and a candle, and we're putting only heat into this beaker, T2 and the temperature goes from T1 to T2.
好的，我们要再次利用这幅图，这有一个敞开的烧杯和一根蜡烛，我们对烧杯加热，温度从T1上升到。
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