那个圆锥头表示正方向。

That conehead indicates a positive direction.

youdao

这个方向，是y的正方向。

And this is the direction, positive direction, of y.

youdao

所以当曲面正方向如此时，结果是正的。

So, in the direction that we are counting positively.

youdao

因为它是可逆的，所以可以正方向运行。

And now since it's reversible, we can run it forward or backward.

youdao

我需要选择一个正方向。

And I need to choose my orientation.

youdao

我把这个选为正方向。

I will now choose this the plus direction.

youdao

,在y的负方向,那么也有一个常力,在y的正方向,这两个力互相抵消。

in the minus y direction and there is a normal force in the plus y direction and these two exactly cancel each other.

youdao

结果得到蓝色矩形，其右下角方向缺少一个正方形区域。

The result is a blue rectangle with a square region toward its lower-right corner missing.

youdao

结果得到蓝色矩形，其右下角方向缺少一个正方形区域。

The result is a blue rectangle with a square region toward its lower-right corner missing.

youdao