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So when I expand this gas adiabatically and it cools down, why do you think it might cool down?
现在我们知道了气体绝热膨胀时,温度会下载，为什么会降温？
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And you already saw last time there was this relationship between the temperature and volume changes along an adiabatic path.
是条绝热路径，而上次你已经看到,沿着绝热路径温度和体积,的变化有这个关系。
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T2 So this is an isotherm at some different temperature T2, a cooler temperature, because this was an expansion.
这个绝热过程的温度是,比T1低，因为这是个膨胀过程。
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That'll be inside our calorimeter. It's insulated, and there's still a thermometer, so we can measure the temperature.
被放置在量热计里面，它是绝热的，同样有一个温度计，让我们可以测量温度。
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OK, so we have constant temperature, because it's isothermal.
好，现在系统有恒定的温度，因为它是绝热的。
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T2 Is the temperature T2 in this process smaller or larger than if I were to do the process reversibly with the same endpoint pressure.
这里的末态温度,与经过可逆绝热过程,到达相同压强的末态温度相比哪个比较高呢？
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We know in an adiabatic expansion the system's going to cool.
我们知道在绝热膨胀过程中,系统温度会降低。
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So we're going to start at one, T1 and this is going to be in isotherm at temperature T1, and all the paths here are going to be reversible.
我们从一开始，这是个绝热恒温过程，温度是，所有路径都是可逆的。
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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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