如图所示,匀质圆盘在光滑水平面上作直线平动。设圆盘的质量为 ,半径为r,轮心C速度为 ,则图示瞬时,对轮心C的动量矩为( ) 。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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