来自《耶鲁大学开放课程：基础物理 第17集 第17集》

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  Don't take a pendulum with all the mass concentrated there.
  这次不再是质量集中的物体
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  Take some irregularly shaped object,
  取某个形状不规则的物体
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  a flat planar object.
  一个平坦的二维物体
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  You drive a nail through it there,
  在这里钉一个钉子
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  hang it on the wall.
  把物体挂在墙上
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  It'll come to rest in a certain configuration
  它会以某种形状保持静止
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  and you should think about where will the center of mass be
  想一想如果我把物体挂在墙上
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  if I hang it like this on the wall?
  它的质心会在哪里呢
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  Center of mass is somewhere in the body here.
  质心会在物体的某个位置
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  So, I want you to think about it.
  我希望你们思考一下
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  I'll tell you in a second.
  我待会会告诉你们
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  The center of mass, they claim,
  物体的质心