我们坐在其中的一列火车上带着特制的速度测量仪，可以测出两列火车之间的相对速度。

We are seated in one of the trains, and with us we have a special speedometer that measures their relative speed.

youdao

结合群众的相对速度测量，可以计算出它们的质量直接明星。

Combining the measured velocity with the relative masses, they can calculate the mass of the star directly.

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这有点像是突然转向的赛车在环形赛道上相撞，月亮们也在同一轨道公转，所以他们之间的相对速度很小。

Like racing cars that swerve and hit each other on a circular track, the moons' speed relative to each other is low because they travel in nearly the same orbit.

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But things which were at rest will move at a constant velocity, opposite of the velocity that you have relative to me.

这些静止的东西都在匀速运动,方向正好跟你相对我运动的速度方向相反

耶鲁公开课 - 基础物理课程节选

In particular, the things that I say are at rest, you will say are moving backwards at the velocity that you have relative to me.

特别是那些在我看来是静止的物体,在你看来却在后退,后退的速度等于我们之间的相对速度

耶鲁公开课 - 基础物理课程节选

That'll say the velocity of the object with respect to the ground, the velocity of the object with respect to the plane, the velocity of the plane with respect to the ground.

可以得到物体相对于地面的速度,物体相对于平面的速度,物体相对于地面的速度

耶鲁公开课 - 基础物理课程节选