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Many people hear it and think it is Mary,M-A-R-Y, instead of M-E-R-R-Y.
VOA: special.2009.12.21
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R is going to be a fix number R times You don't know what it is right now.
等于一个常数 R 乘以,你现在还不知道它是多少
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R/Cv OK, so that means that this is really instead of -1 R over Cv. it's really gamma minus one.
现在,变成了γ
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And we can simplify this expression as saying negative e squared over 4 pi, epsilon nought r squared. Epsilon nought is a constant, it's something you might see in physics as well.
也会遇到它,在这里，你可以就把它,理解为一个转换系数,我们需要做的。
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We notice that the value of E at r naught is negative, as it should be. It's a negative number.
我们主要到在r圈时E的值为负，和它本来的值一致，是一个负数。
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If you do it in monthly terms your interest rate is r/12 because there are twelve months in a year.
如果是每月还款那么月利率是r/12,因为一年有12个月
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At every instant, it's got a location given by the vector R; R itself is contained in a pair of numbers, x and y, and they vary with time.
在每一个瞬时,它的位置由位矢 R 给出,R 本身包含了一对坐标值 x 和 y,并且它们都随着时间的变化而变化
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Cv+R=Cp Cv is equal, oh Cv plus R is equal to Cp it's a relationship that we had up here that we wanted to prove.
我们就得到了,我们一开始,想要证明的。
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It's true for any gas, and if I remove this limit here, r t is equal to p v bar, I'm going to call that an ideal gas.
这样的气体被称作理想气体,这就是理想气体的性质，理想气体的涵义是什么？
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And one common way to think about it, is to think about the value of r, or the radius, below which 90% of that electron density is going to be contained.
而通常的想法，是想象，r，的值，也就是半径的值，即有百分之九十的电子密度,都落在这个范围之内。
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So, let's say we start off at the distance being ten angstroms. We can plug that into this differential equation that we'll have and solve it and what we find out is that r actually goes to zero at a time that's equal to 10 to the negative 10 seconds.
也就大约是这么多,所以我们取初始值10埃,我们把它代入到,这个微分方程解它,可以发现，r在10的,负10次方秒内就衰减到零了。
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I'm going to call it r. It's going to be the gas constant, and now I have r times t is equal to the limit, p goes to zero of p r.
如果去掉p趋于0的条件,在有限压强下都,保持RT=pV的关系。
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There I have it Cp is equal to Cv plus R, right?
所以Cp=Cv+R，对吗？
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We also know how to figure out the energy of this orbital, and we know how to figure out the energy using this formula here, which was the binding energy, -Rh which is negative r h, we can plug it in because n equals 1, so over 1 squared, and the actual energy is here.
我们知道如何算出,这个轨道的能级，而且我们知道如何,用这个公式,算出能量，也即是结合能，等于，我们把n等于1代进来，所以除以1的平方，这就是能量。
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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
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Generally, if it pays c dollars for every period, the present value is c/r.
推广开来,如果在每段时期内支付c美元,那么它的现值就是c/r
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What we do is we take the interest rate, which I'll call r, and plug it into a formula, which I didn't actually do the arithmetic to their number.
我们只需将利率r,代入等式中,虽然我没有代入数字验证过...
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It just turns out that if you put the v^2 and you put the r, and r is 93 million miles, you will find the acceleration is small enough for us to ignore.
这样的话,如果你把 v^2 和 r 代进去,r 是 9300 万英里,你会发现加速度小得足以被忽略
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