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But it's a good story, Joule decided that there must be a direct relationship between work and heat.
所以说，这只是一个不错的故事而已，焦耳认为功和热之间,一定具有某种直接的联系。
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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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So that's the important take-away message from this slide. If we think about these different types of lights, microwave light, if it's absorbed by a molecule, is a sufficient amount of frequency and energy to get those molecules to rotate. That, of course, generates heat, so that's how your microwaves work.
重要的信息，如果我们看看,这些不同种类的光，微波,如果被分子吸收，它的频率和能量可以,使分子转动,这当然的，会产生热量,这就是你们微波炉的工作原理。
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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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One is that he observed when people were machining cannon barrels, a lot of heat was generated, and there was a lot of work done.
第一种说法说焦耳发现,制作加农炮筒时，会产生大量的热，同时这中间有大量的做功。
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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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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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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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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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Delta u, delta H, familiar state functions, q w changes in their values, q, w, heat and work.
U，△H，很熟悉的态函数，它们的值在变化；
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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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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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All heat couldn't get successfully converted into work That would be desirable, but it's not possible.
都变成功,把全部热量变成功是非常令人期待的，但是这是不可能的。
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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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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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Now let's compare what happens to work and heat.
现在让我们比较一下功和热量的变化。
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Or there was a relationship between work and heat.
或者功和热之间有某种联系。
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So here are expressions for work and heat.
这是功和热量的表达式。
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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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You can take heat energy and convert it to work energy and vice versa, and it doesn't say anything about that you have to waste heat if you're going to transform heat into work.
你可以把热能便成功,也可以反过来,但它对于如果你要把热变成功,就必须浪费热量这件事只字未提,它只是说这是能量。
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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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