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So it's grounded in a historical moment, and we'll come back to this and what that might mean about her perception of God.
它在重要的历史时刻落地生根,让我们回到犹太人对上帝的看法，意味着什么。
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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
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We just want to know when he's going to hit the pavement, and with what speed.
我们只关心他什么时候摔到人行道上,以及他落地时的速度
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You shoot something, you should know when it will land, where it will land, with what speed it will land, how high it will go.
抛出一个物体,我们要知道落地时间,落地位置,还有落地的速度,最高点的高度
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So, for example, you know, I'm going to calculate next when it hits the ground.
比如说,我下面要来算,物体何时落地
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That's correct. So her answer was, if it was a full parabola, then we know it would've been at the ground before I set my clock to 0.
她说,如果运动轨迹为一条完整的抛物线,那么它在我们所设定的零时刻之前,就已经落地了
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When does it hit the ground and at what speed?"
该物体何时落地,落地速度是多少
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So you get two answers when it hits the ground.
解出了两个落地时间
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So you cannot use the formula once it hits the ground because once it hits the ground, the fundamental premise that a was a constant of -9.8 or -10 is wrong.
当物体落地以后,该公式就不适用了,因为当物体落地后,公式的基本前提——,加速度为常数-9.8或-10——就不成立了
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When does it hit the ground" is "When is y=0"?
何时落地"也就是"何时位移为零"
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One question is: where is it going to land?
问题一是它在哪里落地
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That tells you where you land.
那你就知道了你在哪里落地
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That's when it hits the ground.
方程的解就是落地时间
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When does the car hit the ground?
车什么时候落地
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So when does it hit the ground?
那么何时落地
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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
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Again, let t* be the time when you hit the ground.
设 t* 为落地的时间
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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
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