I just bring the downstairs to the upstairs.

这里是把下面的写到上面来
Then, remember the wonderful formula I told you?

记得我告诉过你们一个神奇的公式吗
You guys have to know this:

这个你们必须要记住
(1 + x)^n; it is approximately 1 + n·x, if x is very small;

如果 x 非常小 (1 + x)^n 约等于 1 + n·x
x is here, the height over the radius of the Earth,

这里的 x 就是高度除以地球半径
which is obviously tiny, so I can approximate that

显然它非常小可以约等于那个
and I get U = - G·M·m / RE + (G·M·m / RE)^2·h.

得出 U = - G·M·m / RE + (G·M·m / RE)^2·h
This is the potential energy at the surface of the Earth

这部分表达式就是将无穷远设为零势点时
for a guy who thinks of zero infinity.

地球表面的重力势能
This is the change in potential energy,

这是当你运动了一段距离后
when you move a distan.

重力势能的变化
Therefore, if you calculate U of h, minus U of 0,

因此如果 h 点的势能减去 0 点的势能