当质点运动时,其位置矢量也随时间 t 而变化。横向速度就等于径向距离与角速度的乘积
回答: 牛顿01 第二定律:"在直角坐标系中,空间任一点P位置可用x、y、z三个参数来表示,用i、j、k分别表示沿x轴、y轴、z轴的单位
由 marketreflections
于 2011-05-06 09:20:26
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