来自《耶鲁大学开放课程：基础物理 第8集 第8集》

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  the boat moves with a small speed;
  船的速度将会很小
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  then, these two numbers in magnitude will be equal.
  那么等式两边将会相等
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  So, if you're going on one of the big cruise ships,
  所以 如果你从一大船上起跳
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  you jump on the shore,
  想跳到岸上
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  you're not going to notice the movement of the ship,
  你将注意不到船的移动
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  but it technically speaking does move the other way.
  但严密地说 它确实朝相反方向运动了
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  Okay, you're airborne, okay.
  好的 你在空中了
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  Then, a few seconds later you collapse on the shore;
  几秒后你就撞到岸上
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  you're right there.
  你在这里
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  Now, what's happening to the boat?
  现在 船的情况又是怎样呢
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  Is it going to stop now? Your momentum is 0. Yes?
  它要停止运动吗 动量为 0 请讲
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  Yes. Everybody agree? I will repeat that answer,
  是的 大家都同意吗 我再说一遍答案