我不希望梯子滑下来，所以我要求，摩擦力必须小于，或者等于，摩擦力的可能最大值。

Now, I don't want this ladder to slide, so now I have a requirement that the frictional force must be less or equal to the maximum frictional force possible.

youdao

所以只有当,摩擦力,小于或等于最大值的,时候才不会倒。

So now the situation is only safe as long as the frictional force is smaller or equal to the maximum value possible.

youdao

物体运动，并向上加速度，因为摩擦力方向斜上，值为这个。

It is moving, so sure, it's going to be accelerated so the frictional force is in this direction, has this value.

youdao