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问题 计算题

设原子核的电荷量为Q，电子的电荷量为e，静电力常量为k，核外有一个电子在距核为r的轨道上绕核旋转.求此电子的动能.

答案

kQe/2r

根据库仑定律和圆周运动的知识可得：kQe/r2=mv2/r

解得：动能mv2/2=kQe/2r.

阅读理解


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选择题

下列各句中加点的成语的使用，不恰当的一句是（   ）

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