来自《耶鲁大学开放课程：基础物理 第1集 第1集》

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  So, kinematics is a complete description of the present.
  运动学是对现在的完整描述
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  It's a list of what you have to know about a system right now.
  它包含系统当前的全部必要信息
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  For example,
  比如说
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  if you're talking about the chalk--if I throw the chalk,
  这支粉笔 如果我扔出这支粉笔
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  you will have to know where it is and how fast it's moving.
  你就想知道它的位置和速度
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  Dynamics then tells you why the object goes up,
  而动力学则会告诉你为什么物体向上运动
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  why the object goes down and why is it pulled down and so on.
  为什么向下运动 为什么停下来 等等
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  That's dynamics.
  这就是动力学
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  The reason it comes down is gravity is pulling it.
  物体向下运动是因为重力作用
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  In kinematics,
  在运动学中
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  you don't ask the reason behind anything.
  我们不关心现象背后的原因
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  You simply want to describe things the way they are
  你只是单纯描述物体的实际状态