题目内容
如图所示,光滑水平面上,轻弹簧两端分别拴住质量均为m的小物块A和B,B物块靠着竖直墙壁。今用水平外力缓慢推A,使A、B间弹簧压缩,当压缩到弹簧的弹性势能为E时撤去此水平外力,让A和B在水平面运动,球:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006114816744.png)
(1)当B恰要离开墙壁时,A物块的速度大小
(2)当弹簧达到最大长度时A、B的速度大小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006114816744.png)
(1)当B恰要离开墙壁时,A物块的速度大小
(2)当弹簧达到最大长度时A、B的速度大小
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611528690.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611497627.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611528690.png)
试题分析:(1)当B离开墙壁时,A的速度为v0,由机械能守恒有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611543338.png)
解得v0=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611497627.png)
(2)以后运动中,当弹簧弹性势能最大时,弹簧达到最大程度时,A、B速度相等,设为v,由动量守恒定律有2mv=mv0
解得v=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000611528690.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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