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In the summer months, the terrible desert heat slowed the work but did not stop it.
VOA: special.2009.08.12
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And the idea was that gravity did work on the water and falling, and that work led to the generation of heat.
焦耳的想法是,重力对水，做了功。
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And in practical terms, we can define the efficiency as the ratio of the heat in to the work out.
在实际中，我们定义,效率为热与功的比值。
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"We use some kind of light oil that we heat up and we actually work it into the oily feathers.
VOA: standard.2010.06.08
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The relationship between heat and work was initially proposed in the 1940's by Joule.
热量和功的关系首先是,由焦耳在1940年提出的。
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So the maximum work out required the maximum heat in.
因此输出最大的功要求,有最大的热。
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get back to the initial point is going to require some input from outside, like heat or extra work or extra heat or something because you've done an irreversible process.
如果要逆转它,回到初始点，就需要外界的投入，比如额外的功，额外的热量等等,因为你进行了一个不可逆过程。
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Real refrigerators actually work with liquids that go into gases so use the latent heat of the liquid, so it doesn't really work like the Joule-Thomson expansion. So this is real.
液体变成气体来工作,以运用液体的潜热，所以这不是,真正像焦耳-汤姆逊膨胀一样工作,这是真实的气体，不像焦耳。
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Is this possible? That's what the first law says it's possible; work is heat, and heat is work, and they're the same thing. You can break even 100% maybe. So let's go back and see what work is.
00%的效率,我们可以从大气中吸收热量，用来驱动我们的汽车,效率也应该能达到。
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It either had work, got its heat from the surroundings, or it got worked on by the surroundings.
系统从环境中，得到热量。
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So again, for both heat and work we don't get the same result. Now let's look at our special function, right. So here's path A.
所以，再一次说明，对于热量和功,我们得到的结果是不同的,现在让我们看看我们的特殊函数。
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OK, so let's go through this and see what we would do which is to calculate the heat and the work. This is well insulated.
好的，让我们开始然后看看,我们该怎样计算热量和功的大小,这是完全绝热的，所以。
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Just to be clear, so it's heat extracted over the work in.
这等于取出的热量除以做的功，我重写一下这个式子。
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The same temperature increase, work and heat, and we have a relationship between heat and work.
同样的温度升高，功和热，因此我们可以得到功和热的关系了。
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And we had the similar statement by Kelvin about the heat engine that required that some heat gets dumped into a cold reservoir in the process of converting the heat from the hot reservoir into work.
相同的陈述,同样的有开尔文表述：,把热量完全从高温热源,转移至低温热源的过程中,必然有功的输出。
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We're going to find other properties that do care about the history of the system like work, that you put in the system, or heat that you put in the system, or some other variables But you can't use those to define the equilibrium state.
我们还会发现其他一些,与系统的历史有关的性质,比如你对系统做的功，或者你向系统传递的热量，或其他的变量,但你不能用它们,来定义平衡态。
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So we know that in each case the heat is going to be the opposite of the work, but the work isn't the same in these two different ways of getting from here to here, right. So let's just see it explicitly. Here's our qA.
所以我们知道在每种情形下功,与热量相差一个负号,但从这里到这里，在这两条路径,中的功是不同的，对吧？,那么让我们明确地看一下。
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You know the heat isn't going to flow from a cold body to a hot body without putting some work in to make that happen.
大家知道热量不会自发地,从冷的物理流动到热的物理,除非对它做功。
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That is, it gives us the relationship between energy and work and heat.
热力学第一定律阐述了,能量，功和热之间的关系。
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OK, so that means heat is being imparted to the system, right, from the surroundings in a manner that compensates exactly the amount of work done.
好，这表示系统,从外界吸热,吸收的热量与系统,对外做功的值相等。
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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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You couldn't just run something successfully in a cycle and get work out of it, using the heat from the hot reservoir, without also converting some of the heat that came in to heat that would flow into a cold reservoir.
如果一样东西在循环工作过程中,只有热从高温热源中流出，而没有热流入低温热源，那么此过程,不可能对外做功,不可能把所有热。
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And so maybe the work generated the heat.
因此或许功产生了热。
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There's an interplay between the energy inside the gas which is the heat energy which is allowing me to do all that work to be outside, and so I'm using up some of the energy that's inside the gas to do the work on the outside.
即使没有热传递,能量也能以,做功的形式传递出去，气体的一部分内能,转化成了功。
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It might suggest that you could convert all the work to heat.
它暗示我们可以把所有的功转化为热,但是热力学第二定律说。
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And the first law says, well heat and work are different forms of energy, and we can add them, and the path dependence of these two things is somehow cancelled in the fact that we have this internal energy.
热力学第一定律说，热和功是能量的不同表现形式，我们可以把它们加起来,它们与路径相关的部分相互抵消,我们就有了内能。
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So you know, what the second law is doing, in other words, it's putting these restrictions on how well or how effectively we can convert heat into work in the case of the engine, or work into heat extracted in the case of a refrigerator.
你们知道，在热机中，热力学第二定律的作用，换句话说，就是给热量,转化为功的效率,施加限制,或在制冷剂中，对抽取热量,进行限制。
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There's no change in them, and then we also looked at some at non-state functions, work and heat, and saw that those aren't zero going around a cycle. Of course you can do work in a cyclic process, and heat can be exchanged with the environment at the same time.
它们不会有变化，然后我们研究了,一些非态函数，功和热量，并看到,沿着循环行进一周的话,它们并不是零，当然你可以在,一个循环过程中做功，而同时热量可以在系统,与外界环境之间进行交换。
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This is providing work that's being used in here, but if you take the whole outside of the surroundings and this whole thing is the system, no net work, these things cancel each other, and yet heat's going up.
如果把外面的全部当成环境，把这里的全部当成系统,那么就没有净的功，它们相互抵消了，热量向上传输，会发生什么？
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It makes sense, right, because you know we got less work out and delta u is the same right, so it must be that less heat got transferred.
这是显而易见的，因为输出的功更少,且Δu相等，所以需要的热量更少。
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