在绝缘光滑的水平面上，如图1所示有相隔一定距离的两个带同种电荷的小球．让它们从静止开始释放，则两个球的加速度和速度随时间的变化情况是（ ）
A．速度、加速度都变大
B．速度、加速度都变小
C．速度变小、加速度变大
D．速度变大、加速度变小
由于同种电荷间存在相互作用的排斥力，两球将相互远离，距离增大，根据库仑定律得知，相互作用力减小．
由牛顿第二定律得知它们的加速度变小．
随着两球间距离增大，电场力做功正功，电势能减少，总动能增加．所以速度增加，
故选D．
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