题干

如图所示,一半径为R的均匀带正电圆环水平放置,环心为O点,在O正上方h高位置的A点与A′关于O对称.质量为m的带正电的小球从A点静止释放,并穿过带电环.则小球从A点到A′过程中加速度(a)、重力势能(EpG)、机械能(E)、电势能(Ep)随位置变化的图象一定不正确的是(取O点为坐标原点且重力势能为零,向下为正方向,无限远电势为零)(   )

A:

B:

C:

D:

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D

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