那我们怎么得到这单位矢量呢？

Now, how do we get this unit vector?

youdao

还有一个有用的概念就是轨道的单位矢量。

Now, another useful notion is the unit vector to the trajectory.

youdao

这上面有一个帽子表示它是单位矢量，T表示它是切线。

It has a hat because it's a unit vector, and t because it's tangent.

youdao

You can pick your unit vectors, or what are called basis vectors, any way you like.

你可以任意选取单位矢量,或者也可以叫做基矢量,这都随便你

耶鲁公开课 - 基础物理课程节选

They are called unit vectors.

它们叫作单位矢量

耶鲁公开课 - 基础物理课程节选

If you do, the unit vectors are called i prime and j prime, the components of the vector change.

如果这么做,单位矢量就是 i' 和 j',矢量的两个分量也会发生变化

耶鲁公开课 - 基础物理课程节选