They would both start to slide at the same angle and the same kind of rubber.
它们都会在一样的角度开始下滑,前提轮胎是用的一种橡胶做的。
2
I have here that same ladder, and now what I will do is I will set the angle alpha not exactly at the critical point but a little lower, so that when I let it go, we'll all see that it will slide.
We know from experience that if this Angle is too small that the ladder will slide, and so I want to make the topic today "What should that Angle be so that it does not slide?"