What makes up a rope? Of course you know, ropes are basically bundles of fibers, very same fibers that have been woven together in a certain way.

绳子是由什么构成的？，你肯定知道，是由一束束纤维构成，是由一样的纤维按某种方式编织,在一起构成。

耶鲁公开课 - 死亡课程节选

Now we really do have two ropes.

现在真的有2根绳子。

耶鲁公开课 - 死亡课程节选

We know there is no thing called a massless rope, but most ropes have a mass, but maybe negligible compared to the two blocks you are pulling, so we'll take the idealized limit where the mass of the rope is 0.

我们都知道无质量的绳子是不存在的,是绳子就有质量,但是相比于这两个物体就可以忽略不计了,所以我们有了这个理想的条件,即绳子的质量都是 0

耶鲁公开课 - 基础物理课程节选

the ropes will be pulling the block with T in the other direction, then I got 10 Newtons here.

绳子也会对另一物体施加方向相反的拉力 T,于是我知道这里是 10 牛顿

耶鲁公开课 - 基础物理课程节选