来自《耶鲁大学开放课程：基础物理 第10集 第10集》

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  then we learned how to find the acceleration.
  然后我们就了解了如何求加速度
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  Then, I took other cases
  接着 我举了另外的例子
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  where there are many bodies exerting a mutual force on each other.
  不同物体的相互作用
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  Then, if there are no external forces,
  如果没有外力作用
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  we saw the total momentum of the system is conserved.
  我们认为系统的总动量是守恒的
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  We're going to do analogous things with our newfound equation of τ=I·α.
  我们要类比一下新学的方程 τ=I·α
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  You want to get used to this more.
  你们要多用这个方程
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  That's all I'm going to do from now on.
  下面就是我为了这个式子所要做的
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  I already told you the beginning,
  我已经告诉你们开头了
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  the new thing you learned was τ=I·α, and we're going to use it.
  新学的式子是 τ=I·α 我们要用到它
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  So, let's take various situations where we can do this.
  让我们来举一些要用到这个方程的例子吧
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  Let me take a simple example.
  我来举个例子