Inside the car, they should open a window a little for fresh air and turn on the engine for ten or fifteen minutes every hour for heat.
VOA: special.2010.01.05
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。
You've just built a heat engine.
加热使压强增加。
In that process there is a metabolic engine at work, and some people have an efficient engine so that the calories in get banked in the fat, other people have an inefficient engine, that is the calories get wasted as body heat and things like that, and they tend not to gain weight.
这过程中人体内有个工作着的代谢引擎,有些人的代谢引擎效率很高,热量便转化为脂肪储存起来,另一些人的效率低下,能量就以体温等形式被浪费了,因此他们就不容易发胖
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。
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。
And these verbal descriptions lead to some pictures that I put up and I'll put up again about how you might try to accomplish something like run an engine or move heat from a colder to a warmer body.
这些言语的描述有助于你们理解我讲过的,而且还要再讲的一些物理图像,比如一台发动机,是怎么运行的,或热怎样从冷的物体传到热的物体。
It expands. You change your constraints on your system, you heat it up some more, then you take the heat source away, and you put it back in contact with the atmosphere. And you cool it a little bit, change the constraints, cool it a little bit more, and heat, and you've got a closed cycle engine.
让它与大气接触冷却,改变约束,使它继续冷却,然后又再次加热,这就是循环热机,我们以前也研究过,更复杂的机器。
So the way I've got things written here, q1 Heat's flowing from the hot reservoir to the engine that runs in a cycle.
我把这些都这些这里,是正的,q1,is,positive,热从高温的热源,传到循环工作的热机,对外做功。
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