来自《耶鲁大学开放课程：基础物理 第16集 第16集》

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  But remember now, the truth is the relativistic theory.
  但是应该牢记 相对论描述真实的情况
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  We're going to go back to Newtonian days,
  而我们现在又回到了经典力学
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  and the reason we do it that way is to give you something interesting,
  希望能给出一些有趣的东西
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  hopefully, compared to what you normally do.
  比你平常做的要有趣的东西
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  So, what we're going to study now is
  下面我们将要研究的是
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  what's called small oscillations, or simple harmonic motion.
  震荡的运动 即简谐运动
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  It's a ubiquitous fact, that if you took any mechanical system
  有一个普遍的事实是 如果研究某一力学系统
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  which is in a state of equilibrium,
  它处于平衡状态
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  and you give it a little kick, it vibrates.
  你对它施加一个外力 它就发生振动
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  Now, if you've got a pillar, ceiling to floor,
  如果现在有一根悬挂在天花板上的柱子
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  you hit it with a hammer, it vibrates.
  你用锤子敲打它 它就振动
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  If you take a gong and hit it, it also vibrates.
  如果敲一面锣 它也会振动