If you want to know something like when do you hit the ground, I think it's fairly clear what you have to do.

如果你想知道车子何时落地,我想你该做什么就很明显了

耶鲁公开课 - 基础物理课程节选

and you've got to hit a ball which is on the ground with a sort of croquet mallets.

你要用一个类似木槌的东西去打击地上的球。

知道马球吗？ - SpeakingMax英语口语达人

For example, if t* is the time you hit the ground, then t* satisfies the equation h - 1/2 g ^2 = 0.

例如,如果在 t* 时刻落地,那 t* 就满足等式 h - 1/2 g ? ^2 = 0

耶鲁公开课 - 基础物理课程节选

you can hit the ground running, as we say.

也就是说，你可以立刻进入状态。

写推荐书的人 - SpeakingMax英语口语达人

Again, let t* be the time when you hit the ground.

设 t* 为落地的时间

耶鲁公开课 - 基础物理课程节选

Conversely, if you get an answer and it doesn't seem to make sense, then you've got to go back and ask, am I violating some of the assumptions, and here you will find the assumption that the particle had that acceleration a is true as long it's freely falling under gravity but not when you hit the ground.

反过来说,如果你得到一个结果,发现似乎是错的,那么你就应该回过头来问问自己,我是不是违反某些前提了,这个模型中,你就发现,只要质点在重力作用下自由下落,质点具有加速度a的前提是正确的,但是落地后就不成立了

耶鲁公开课 - 基础物理课程节选

We want to know, as you can tell-- our concern is where does the car hit the ground?

我们想知道,你们也能算出来,车将在哪一点落到地面

耶鲁公开课 - 基础物理课程节选