So what we've discovered from this relationship dq that du at constant volume is equal to dq v.
从这个关系式里我们发现,恒体积时的du等于恒体积时的。
A It tells me that the partial of A with respect to T at constant V is minus S. Right?
他告诉我们,在恒定体积下对温度的微分等于负S,对吗?
Why is that? Because w and v are constant.
为什么?因为w和v是常数。
Whenever you see a particle moving in a circle, even if it's at a constant speed, it has an acceleration, v square over r directed towards the center.
只要看到质点做圆周运动,即使是匀速圆周运动,也存在一个加速度,大小为 v^2 / r,方向指向圆心
So the first path then, the first path, 1 constant volume constant V, so I'm going to, again, let's just worry about energy.
首先,是路径,等压过程。
du/dT And we discover that du/dT at constant V T is equal to du/dT at constant V.
可以发现恒定体积下的,等于恒定体积下的偏u偏。
OK, so for a constant volume process, du we can write du, partial derivative of dT u with respect to T at constant V, dT, dv plus partial derivative of u at constant V, dV.
好,对于一个恒定体积的过程,我们可以写出,等于偏u偏T,V不变,加上偏u偏V,T不变。
Normally I couldn't do that Vdp because this term would have p dV plus V dp, but we've specified the pressure is constant, so the dp part is zero.
一般情况下我不能这么写,因为这一项会包含pdV和,但是我们已经假定压强为常数,所以包含dp的部分等于零。
So we immediately get du at constant S and V is less than zero.
这样我们马上就得到以下结论:,在等熵,等容条件下dU必须小于零。
V All right, or p is equal to a constant divided by volume.
或者p等于常数C除以。
I'm pressing on the gas. So I expect that to be a positive number. The pressure is constant 0 p. The V goes from V1 to zero.
我们对气体加压,所以这应该是一个正数,压强是常数,p,V从V1变成。
And so now we have this quantity, p times v bar, and the limit of p goes to zero is equal to a constant times the temperature.
不仅仅对氢气或氮气适用,在p趋于0的极限下,它适用于任何气体。
take the derivative of this, get the velocity vector and you notice his magnitude is a constant Whichever way you do it, you can then rewrite this as v square over r.
对这个式子求一次导,就能得到速度矢量,你会发现其模长是常数,不管用什么方法,加速度也可以写成 v^2 / r
Well, we already know what dA/dT at constant V is.
我们知道恒定体积下的。
v du/dV under constant temperature. du/dT v under constant volume. You use the Joule expansion to find these quantities.
像偏u偏v,恒温下的偏u偏,恒容下的偏u偏,你们知道怎么运用焦耳定律。
This depends on the path. It tells you right here the path is constant pressure. These don't depend on the path, right. V doesn't care how you v get there. u doesn't care how you get there.
这由变化的具体路径决定,这个小脚标表明过程是恒压的,这些量都与具体路径无关,即不管是通过什么路径使得体积变化为Δ
SV And this is, of course, with constant S V.
当然在这里是保持恒定的。
Then you take p1 to p2 with V constant.
图上画出来就是这样。
V So it's minus T dV/dT at constant p, plus V.
负的T乘以恒定压强下dV/dT,再加上。
The ideal gas constant doesn't change, temperature doesn't change, and so v we just have minus nRT integral V1, V2, dV over V.
理想气体常数不变,温度也不变,因此,是负的nRT,积分从v1到v2,dv除以。
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