来自《耶鲁大学开放课程：基础物理 第5集 第5集》

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  And this is the velocity and c is the velocity of light.
  这是物体的速度 c 是光速
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  This is the exact formula.
  这是精确计算公式
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  Now, most of the time we don't care about it
  多数时间不会用到它
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  because v / c maybe 10^(-10)
  因为 v / c 可能等于 10^(-10)
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  and the square of that is 10^(-20)
  平方以后就是 10^(-20)
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  and one minus such a number is negligible
  1 减去这样小的一个值
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  and we just put it as one.
  我们可以认为它仍是 1
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  Suppose you want an answer that's good to some accuracy.
  如果你想要精确度更高的答案
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  I will write this as follows,
  我会这样写
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  do you agree?
  同意吧
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  That's what a square root in the bottom is,
  在下面时平方根这样表示
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  it's this power upstairs.
  在上面是这样