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。
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。
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。
All the energy that is inserted into this, which might be turbulence initially, becomes heat, or becomes -- it raises the temperature.
由振动引起的所有,进入系统的能量最后都变成了热,因此温度便升高了。
So if I worry about energy I have a pretty good chance of extracting out these heat capacities, right, and I don't have to worry about exactly which path and I can really mix things up.
而能量与热容有密切的关系,从能量就可以就算出这两个热容,我不需要考虑到底是哪一条路径,可以随意计算。
Otherwise you're going to waste some of that heat somewhere along the way, some of energy.
否则你就必须在这个过程中,浪费一些热量。
That is, it gives us the relationship between energy and work and heat.
热力学第一定律阐述了,能量,功和热之间的关系。
You're always wasting energy into heat somewhere when you dochange that involves mechanical change.
当进行与机械运动有关的变化时,总会有能量变成热量而被浪费掉。
We have discovered that this partial derivative that appears in the definition, the abstract definition of the differential for internal energy, is just equal to the constant volume heat capacity.
我们还发现,这个偏微分出现在了,内能的偏微分,定义式中,它也就是热容。
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。
And because there is an explicit relationship between u, delta u, q and w, you can always find the easy way to derive the change in internal energy or the heat or the work.
因为Δu,q和w之间,有明确的关系,一般来说,内能或热或功的变化,易于计算。
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