来自《耶鲁大学开放课程：基础物理 第10集 第10集》

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  which is rate at-- which goes round and round.
  这是它做转动的速率
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  It's the usual frequency times 2π
  角速度是频率乘以 2π
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  because 2π radians are full circle.
  因为圆周的弧度是 2π
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  Then, it has an angular momentum,
  然后 它有个角动量
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  which is the analog of the mass,
  它等于类比的质量
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  times analog of the velocity, as is universally noted by the symbol L.
  乘以类比的速度 通常记为 L
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  Then, if you want to change this angular momentum,
  如果你想要改变角动量
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  it's like asking,
  这就像问
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  "How do you change the ordinary momentum of a particle? "
  "如何改变一个粒子的平动动量"
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  You apply a force.
  你需要施加力
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  So, now we apply what's called a torque.
  那么 我们现在施加所谓的转矩
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  And the torque is the reason the angular momentum changes.
  转矩就是角动量改变的原因