来自《耶鲁大学开放课程：基础物理 第1集 第1集》

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  and predict the future given the present.
  根据现状 预测未来
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  So the problem I want to do--
  我想讲的这道题
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  there are many things you could do
  类似的题目很多
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  but I just picked one,
  但我就选了其中一个
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  and this is the one with round numbers,
  这道题涉及的数字都是整数
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  so I can do it without a calculator.
  所以我不需要计算器
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  Here's the problem.
  题目是这样的
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  There is this building
  这是一栋大楼
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  and it's going to be 15 meters high,
  它有15米高
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  and I'm going to throw something
  我会抛出某个物体
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  and it's going to go up and come down.
  它将先上升后下降
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  It's something I throw up
  抛出物体的