它可以被称为多向矢量性时间之门。

It may be termed a time-gate vector.

youdao

根据它的原理，我们通常用v表示,这里的V更代表速率而不是矢量，你能通过,对一个关于时间的位置向量求导得到它。

And, the way we can get it, so, it's called usually V, so, V here stands for velocity more than for vector. And, you just get it by taking the derivative of a position vector with respect to time.

youdao

你可以说，位置矢量在另一个时间或在任何时间，无论如何，位置矢量始终在这个平面上。

You could say the position vector at another time, or at any time, but in fact, what's also true is that the velocity vector is in the plane.

youdao

Just take the derivatives and that's the velocity vector.

直接计算对时间的导数就是速度矢量

耶鲁公开课 - 基础物理课程节选

Mathematically, it's done by taking the expression for R and differentiating everything in sight that can be differentiated as vector t.

从数学上看是这样的,写出 R 的表达式,并对所有可以进行矢量微分的部分,对时间 t 求微商

耶鲁公开课 - 基础物理课程节选

Because the difference in the vector between two times is this vector.

因为两个不同时间点上矢量的差,就是这个矢量 ΔR

耶鲁公开课 - 基础物理课程节选