R平方

你知道球体的表面区域，是4pi，r平方，因此你能计算，每平方米多少，抵达地球。

You know that the surface area of this sphere is four pi r squared , and so you can calculate how much for every square meter reaches the Earth .

，力，重力，随着r的平方而减少。

The force , gravitational force , falls off as one over r squared .

我们得到结论-，重力加速度，随r的平方而减少。

We came exactly to that conclusion & that the gravitational acceleration falls off as one over r squared .

因此你看到，我承受的重力加速度，距离地球不同远近，距离太阳的不同距离，和r的平方成反比。

And so you see that the gravitational acceleration that I experience at different distances at different distances from the sun , is inversely proportional with r squared .

用这个方程，对于s轨道，径向概率分布，4πr的平方，乘以波函数的平方，这很容易理解。

So , we can do that by using this equation , which is for s orbitals is going to be equal to dr4 pi r squared times the wave function squared , d r.

如果你们数的话，原子核的数是，我们用它乘以πr的平方，得到横截面积，除以1。

So , the number of nuclei , 119 if we were to sit and count these as well , is119 . So , we 'll multiply that by just pi , r squared , to get that cross-section , and divide all of that by1 .

这两个力相同，除了，我的力沿着这个方向-，这是r的增长方向-，所以我的力是，除以r的平方，如果我在这个位置。

The two are identical except that-mine is in this direction this is increasing value of r + mMG so mine would be plus m MG divided by r squared if I 'm here at location r.