如图所示,粗糙程度均匀的绝缘斜面下方O点处有一正点电荷,带负

如图所示,粗糙程度均匀的绝缘斜面下方O点处有一正点电荷,带负电的小物体以初速度V1M点沿斜面上滑,到达N点时速度为零,然后下滑回到M点,此时速度为V2V2V1 )。若小物体电荷量保持不变,OMON,则

   

A.小物体上升的最大高度为

 

B.从NM的过程中,小物体的电势能逐渐减小

C.从MN的过程中,电场力对小物体先做负功后做正功

D.从NM的过程中,小物体受到的摩擦力和电场力均是先增大后减小

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