来自《耶鲁大学开放课程：基础物理 第8集 第8集》

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  What's the equivalent way to say that? Yes?
  还有哪些说法与此等价呢 你来说
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  Right, the momentum cannot change.
  是的 系统的动量不会变化
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  Originally, the momentum was 0, nobody was moving,
  初始时系统的动量为 0 各物体都静止
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  but suddenly you're moving, the boat has to move the other way.
  你突然开始运动 船就得朝相反方向运动
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  Of course, it doesn't move with the same velocity,
  当然它以另一速度运动
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  or the same speed; it moves with the same momentum.
  它的动量与你相同
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  So, the big M of the boat times the small v of the boat,
  所以 船的质量乘以船的速度
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  will equal your small m times your big V.
  将等于你的质量乘以你的速度
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  In other words, you, unless you move with a big speed,
  换句话说 除非你以一较大速度移动
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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