因此我决定，在此处改变正方向，加速度方向就始终为正了，符号变了。

So the moment that I decide to define this the plus direction will also come out to be the same sign as this one so I flip the signs there.

youdao

在太空中，计算机被用来控制宇宙飞船的速度和方向。

In space, computers have been used to control the speed and direction of a spaceship.

youdao

有些种类的蝙蝠会根据回声频率的变化来调整向猎物移动的方向和速度。

Responding to changes in the CF echo's frequency, bats of some species correct in flight for the direction and velocity of their moving prey.

youdao

It comes from the fact that velocity is a vector and you can change your velocity vector by changing your direction.

其原理就是,速度是矢量,你可以通过改变方向来改变速度

耶鲁公开课 - 基础物理课程节选

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

And I could take that information, type it up into a program, make some assumptions about speed and direction and what routes they're going to take and actually watch the ambulance go to St. John's Mercy.

我得到这条信息之后，将它输入程序里，假设它们的速度和方向,以及它们应走哪条线路,就能看到救护车进入圣约翰医院。

斯坦福公开课 - Twitter之父Jack.Dorsey演讲：好奇和灵感的力量课程节选