来自《耶鲁大学开放课程：基础物理 第4集 第4集》

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  This is like an amusement park,
  就像游乐场里一样
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  so that they have these dangling little, tiny, baby rockets
  那里有给小孩子坐的摇晃小火箭车
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  and you sit there and start spinning,
  你坐的那里开始旋转
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  and instead of being vertical,
  小车并不会保持竖直
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  it starts lifting up,
  而是慢慢升起来
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  and you want to know why it's lifting up.
  你想知道它为什么会升起来
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  So, if this angle here is θ, and this is some mass m,
  如果这个角是 θ 它的质量是 m
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  and it's going around in a circle with velocity v,
  以速度 v 做圆周运动
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  and the radius of the circle is say r;
  圆的半径为 r
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  we want to find some relation between this angle θ
  我们要找出这个角度 θ
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  and these other parameters in the problem.
  和题目中其它参数的关系
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  So what do I do?
  我该怎么做呢