题目内容
如图,可当做质点的A、B两个物体质量均为m,A带电量为+q,B不带电,A、B与固定斜面的动摩擦因数均为
,斜面倾角为
.斜面长度为L,处在水单向左的匀强电场中,A恰好可沿斜面匀速下滑。求:
(1)水平电场的电场强度大小是多少,
(2)若A处在斜面中点以某速度匀速下滑时,B刚好在斜面顶端由静止下滑,且A、B恰在斜面底端相遇,则A匀速下滑的速度大小为多少。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241149228916646.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114922844204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114922875200.gif)
(1)水平电场的电场强度大小是多少,
(2)若A处在斜面中点以某速度匀速下滑时,B刚好在斜面顶端由静止下滑,且A、B恰在斜面底端相遇,则A匀速下滑的速度大小为多少。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241149228916646.gif)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923000864.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241149229071042.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923000864.gif)
(1)A匀速下滑时:
………………①
……………………②
……………………③
得:
………………④
(2)B沿斜面向下匀加速时:
………………⑤
……………………⑥
对
……………………⑦
得:
……………………⑧
评分细则:①②③共4分,直接写
也给4分,④4分,⑤⑥⑦⑧各2分,共16分。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923016699.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923031711.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923047398.gif)
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241149229071042.gif)
(2)B沿斜面向下匀加速时:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923078711.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923094455.gif)
对
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923109463.gif)
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114923000864.gif)
评分细则:①②③共4分,直接写
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241149231411069.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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