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so I'm heating up the system in this path here, and then to connect the 2 endpoints here, a constant temperature path.
需要再用，一个等温过程，这两个状态。
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Adiabatic meaning there's no heat involved, and we're going to see how that differs from the isothermal expansion and compression.
绝热意味着没有热量的传递，我们将看到它,与等温过程的区别。
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So then, going from the initial to final states with a red path, ou start with an isobaric processand then you end with an isothermal process.
因此沿着,这条红色路径，你从一个等压过程开始,以一个等温过程结束。
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PROFESSOR BAWENDI: So the question was, for an isothermal expansion, delta u does not change, therefore, The answer is that's true only for an ideal gas.
你的问题是，在等温过程中，内能是否，这只对理想气体成立。
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Instead of this reversible isothermal step, Let's make it an irreversible isothermal step.
不是可逆等温过程，而是不可逆等温过程。
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As long as it's reversible, you know what the efficiency has to be, and in principle, you could break it down into a bunch of steps that you could formulate as isothermal and adiabatic.
只要这个循环过程是可逆的，你们知道效率是多少，从理论上说，可以将总过程,分解成一系列绝热,和等温的小过程。
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So there's going to be a line that's going to connect the initial point to the final point, and that line mathematically is not going to be the same as this one here.
连接绝热过程,初末态的曲线的方程，和等温线的方程,也不会相同。
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For isothermal expansion, that means that delta u does not change, but delta q is equal to delta w?
在等温过程中，是不是内能不变，Δq等于Δw？
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PROFESSOR BAWENDI: So, for an ideal gas, the isothermal is the easy one because the energy doesn't change.
对理想气体，等温过程最简单,因为能量不变。
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So I'm going to write that immediately here, u=0 because I know the answer to that path here.
等温过程，我们可以得到，Δ
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So the connection between this endpoint here, and that one here. Same temperature.
我们可以用一个，等温过程连接它们。
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of the night what you say, isothermal process, what do you say?
等温过程，怎么回答？
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Path number 3 is a constant temperature path, and I already wrote the answer.
它是一个等温过程，我已经写出了答案。
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We can have a different isothermal step.
这是一个不同的等温过程。
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Ideal gas only depends on the temperature, the energy only depends on the temperature.
只依赖于温度，因此等温过程中。
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So from one to two it's isothermal.
从一点到二点是等温过程。
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Constant temperature means isothermal, so this part means an isothermal process.
等温“指温度不变，这部分就是指一个等温过程。
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It's going to be an isothermal path that's going to connect them.
用等温过程,来连接。
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And you know, you could have a reversible engine with lots and lots of steps, but you could always break them down into some sequence of adiabatic and isothermal steps.
你们知道，我们可以设计一个由，很多很多个,循环步骤的热机，但是总可以把它分割成,一系列的绝热,和等温过程。
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u=0 Constant temperature isothermal delta u is zero.
对等温过程，Δ
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All right so we know how to do this.
研究了等温过程后。
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We don't know if it's bigger or smaller.
到底比等温过程的值大还是小。
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So this is an isothermal expansion.
这是个等温膨胀过程。
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This is going to end up at a different temperature by the way. You saw this last time in a slightly different way. Last time what you saw is we compared isothermal and adiabatic paths that ended up at the same final pressure, and what you saw is that therefore they ended up in different final volumes.
末态温度是不一样的,上次你们看到的,和这个有一点不一样,上次我们比较的是末态压强,相等的等温过程和绝热过程,因此它们的末态,体积是不一样的。
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All right, so gamma, the gas is cooling so V2 is going to be less than it what would be if the temperature kept constant.
气体温度下降了,于是V2会比等温过程,降到相同压强时的体积要小。
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