来自《耶鲁大学开放课程：基础物理 第7集 第7集》

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  And unless you specify the path you cannot do the integral,
  除非给定路径否则无法求积分
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  because you don't know what contour you want to draw.
  因为你不知道路线
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  Therefore, the answer in general depends on the path,
  因此 答案一般都和路径有关
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  but this right-hand side does not.
  但等式右边和路径无关
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  So, if you pick the same two endpoints
  所以 如果选择两个相同的终点
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  and you vary that path into this one,
  然后将那条路换成这条
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  the right-hand side doesn't change,
  右边不变
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  but it's not hard to imagine
  不难想象
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  the left-hand side would be different.
  左边会改变
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  Therefore, in general this will not be true.
  因此 一般来说等式不成立
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  So, even though there's a relation between work done
  所以 虽然对物体所做的功
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  and increase in kinetic energy,
  和其动能增量之间有关联