假如速度不变，则距离随时间增 大。

On the assumption that speed is kept constant, distance increases with time.

youdao

其中一个前提是，光的速度不变。

One of them is: the velocity of light is invariable.

youdao

你们速度不变，会发现我速度在变化。

And you sit there and you say, "Aha, his velocity is changing."

youdao

That's another way of saying maintaining velocity if it's not acted upon by a force.

这就是不受外力作用时,速度保持不变的另一种说法

耶鲁公开课 - 基础物理课程节选

The Law of Inertia says that, "If a body has no forces acting on it, then it will remain at rest if it was at rest to begin with, or if it had a velocity to begin with, it will maintain that velocity."

惯性定律就是,"如果一个物体不受外力作用,那么静止的物体依然保持静止,如果物体有个初速度,那么就保持此速度不变"

耶鲁公开课 - 基础物理课程节选