So, if instead you put your particle somewhere down here on the electric field, or on the wave, the electric field will now be in the other direction so your particle will be pushed the other way.

还有方向，所以如果,你把粒子放在这下面，电场的方向相反,粒子会朝另一个方向运动。

麻省理工公开课 - 化学原理课程节选

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

Because once things started moving, it tends to move in that direction.

因为一旦事物开始改变，他们就会有朝这个方向运动的倾向。

麻省理工公开课 - 计算机科学及编程导论课程节选

And she's had the opportunities since MAPP to actually teach a lot of the courses and she's very focused on goal setting and she's very focused on sports psychology.

攻读硕士学位后,她获得很多授课的机会,她的方向是目标设立,和运动心理学。

哈佛公开课 - 幸福课课程节选

This particle is constantly changing its direction, but it therefore has an acceleration and the acceleration, we have shown here, is pointing towards the center.

这个质点恒定地改变它的运动方向,因此它具有加速度,而且这个加速度,我们前面也讲过了,指向圆心

耶鲁公开课 - 基础物理课程节选

But if I see you through the glass, the object is going on some trajectory, which has got both up and down and horizontal motion.

但是如果我透过窗户看到你,这个物体沿着某个轨迹运动,既有上下,也有水平方向的运动

耶鲁公开课 - 基础物理课程节选

You can deduce it because the carriage is moving the other way.

你能推出这个结果因为车厢在朝反方向运动

耶鲁公开课 - 基础物理课程节选

The fact that you don't need a force for it to move forever at a given speed in a given direction, that's not obvious, because in daily life you don't see that.

对于物体不需要力的作用就能保持,确定的速度和方向持续运动这一事实,它并非显而易见,因为在日常生活中你看不到这种情况

耶鲁公开课 - 基础物理课程节选

It tells you when a particle moves in a circle, it has an acceleration in a negative R direction, namely directed towards the center.

它告诉你当一个物体在圆周上运动时,它有一个在 -R 方向的加速度,也就是说是直接指向圆心的

耶鲁公开课 - 基础物理课程节选

Whenever you see a particle moving in a circle, even if it's at a constant speed, it has an acceleration, v square over r directed towards the center.

只要看到质点做圆周运动,即使是匀速圆周运动,也存在一个加速度,大小为 v^2 / r,方向指向圆心

耶鲁公开课 - 基础物理课程节选

The motion is just along the x axis.

只有 x 轴方向的运动

耶鲁公开课 - 基础物理课程节选

Quite often, it's natural to pick x and y in a certain way, because starting a projectile near the Earth, it makes sense to pick the horizontal as x and vertical as y.

我们经常会很自然地选取 x 轴和 y 轴,因为如果在地表附近做抛物运动,我们通常以水平方向为 x 轴,竖直方向为 y 轴

耶鲁公开课 - 基础物理课程节选