题目内容
如图甲所示,平行金属板中央有一个静止的电子(不计重力),两板间距离足够大.当两板间加上如图乙所示的交变电压后,在下图中,反映电子速度v、位移x和加速度a三个物理量随时间t的变化规律可能正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500265427333610.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500265427333610.png)
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试题分析:分析电子一个周期内的运动情况:0~
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654288394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654288394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654320416.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654320416.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654320416.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654366476.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654366476.png)
A、根据匀变速运动速度图象是倾斜的直线可知A符合电子的运动情况.故A正确.
B、电子做匀变速直线运动时x-t图象是抛物线,故B错误.
C、根据电子的运动情况:匀加速运动和匀减速运动,而匀变速运动的加速度不变,a-t图象应平行于横轴且
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654320416.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002654366476.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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