如图所示,在光滑的水平绝缘桌面上,带电小球A固定,带电小球B在A

如图所示,在光滑的水平绝缘桌面上,带电小球A固定,带电小球B在AB间库仑力的作用下以速率v0绕A做半径为r,的匀速圆周运动若使其绕A做匀速圆周运动的半径变为2r,则占球的速度大小应变为                  (    )

       A.    B.

       C.  D.

答案

A

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