So, the force of friction is different

所以摩擦力的大小
when it's moving as compared to when it's not moving,

在运动和静止时相比是不一样的
it's slightly less, once a body is in motion.

一旦物体运动起来摩擦力就会稍小一点
So, it's always true for all situations;

有一点是永远正确的
μ sub-kinetic is less than μ sub-static.

动摩擦系数比静摩擦系数小
Okay? So, this is how you characterize friction.

我们就是这么描述摩擦力的
You study various objects

我们研究不同的物体
and you find out friction certainly depends on

并且发现摩擦力其实是取决于
on the nature of the two surfaces.

两个物体接触面的性质
Given that constant,

只要接触面性质是给定的
it seems to depend only on the normal force and not on the area.

摩擦力就只取决于法向力而和面积无关
Yes?

说吧