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So, the total work that we can get out must be zero, out of the whole sum of them.
因此，我们可以从这两个热机,得到的总功，一定是零。
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You could say, I could have zero chickens and 20 pigs, does that work? I've got one chicken and nineteen pigs, does that work?
为什么简单列举出所有可能的情况,再一个来检验？你可能会说,我可以有0只鸡和20只猪，这能行吗？
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Right, 'cause that means either I've been handed zero elements which mean there's really no work to be done or I've been handed one element which is a vacuous truth that it's sorted, right?
因为如果给出0个元素,那意味着不需要做任何事,如果给出1个元素，那显然,它是有序的，对吗？
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This piston is being brought out, so we expect 0 the work to be negative, negative. And we start o V2 ut with zero volume. We end up with a volume p2 of V2, and the external pressure is constant to p2.
所以我们可以想象功是负的,开始的时候体积是,最终的容积是,外界的压力恒为。
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But the important part here is that the work is not zero. You're starting at one point.
从任意一点出发,完成一个循环。
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And there is no work done on the surroundings because pressure is zero.
这里系统没有对环境做功,因为压强是零。
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If there's no work to be done, 0 the running time is gonna be zero.
如果并不需要做什么，那么其运行时间肯定为。
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So if delta v is negative, in this case delta v is negative, OK, delta v is negative, pressure is a positive number, negative times negative is positive, work is greater than zero.
也就是当活塞,压缩气体的时候，做的功是正的，按照这一规定,我们需要在这里，加上一个负号，这是习惯规定。
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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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The total work is less than zero.
说明系统对外界做功。
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So q is zero adiabatic. Work is zero.
因为系统绝热，所以q是零。
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q Work is zero. Delta u is w plus q, work plus heat. This is zero, this isn't.
功是零，△U是w加，功加上热量，这个是零。
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Did no work. Does that mean du is zero?
没有对外做功，这是否意味着du=0？
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And it's p external and p external is zero, so there's no work.
外部的p是零，所以结果是零，没有做功。
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