When you're falling to the surface of the Earth, you are describing a problem of constant acceleration.

当你讨论下落问题时,你在描述一个加速度恒定的问题

耶鲁公开课 - 基础物理课程节选

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

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I want to consider a particle which has definite acceleration a, a constant one, but a is now a vector.

我想考虑一个加速度为 a 的质点,加速度恒定,但 a 是一个矢量

耶鲁公开课 - 基础物理课程节选

We said, "Let's take, for the simplest case that we can possibly imagine, namely a particle moving in one dimension along the x-axis with a constant acceleration a.

我们说过,"考虑我们可以想象的最简单的情况,即质点在一维空间运动,沿着 x 轴且保持恒定加速度 a

耶鲁公开课 - 基础物理课程节选