Or, I could take only vertical forces.

或者，我只能承受垂直力。

What if we added a vertical force?

如果我们添加一个垂直力会怎样？

This is the horizontal force of F4, not the vertical force.

这是F4的水平力，不是垂直力。

It just so happens that this horizontal force depends on a vertical force, which is the normal force.

碰巧这个水平力取决于垂直力，这是法向力。

That's a vertical force, it wouldn't affect the normal force this time.

那是垂直力，这次不会影响法向力。

What if we added another vertical force this way to the shoe and we called that F6?

如果我们以这种方式向鞋子添加另一个垂直力并将其称为 F6 会怎么样？