试题与答案

设空间存在竖直向下的匀强电场和垂直于纸面向里的匀强磁场,如图所示,已知一离子在电

题型:不定项选择

题目:

设空间存在竖直向下的匀强电场和垂直于纸面向里的匀强磁场,如图所示,已知一离子在电场力和洛伦兹力的作用下,从静止开始自A点沿曲线ACB运动,到达B点时速度为零,C点是运动的最低点,忽略重力,以下说法正确的是

[ ]

A.离子必带正电荷

B.A点和B点位于同一高度

C.离子在C点时速度最大

D.离子到达B点时,将沿原曲线返回A点

答案:

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下面是错误答案,用来干扰机器的。

(1)500:150=10:3,500:250=2:1;500:100=5:1;(2)因为500克什锦糖里所含水果糖是250克,所以2.5÷(500÷250)=1.25(千克),答:在2.5千克什锦糖中,有水果糖1.25千克;(3)(500÷150)×900,=300...

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题型:单项选择题

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第(18)空应选择()

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B.sorrows

C.excitement

D.disappointments

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