题目内容
(18分)如图所示,在倾角为θ的光滑斜面上放有三块小物块,劲度系数为k1的轻质弹簧两端分别与质量为m1和m2的物块A、B拴接,劲度系数为k2的轻质弹簧两端分别与质量为m2和m3的物块B、C拴接,物块C紧靠挡板,整个系统处于平衡状态.现施力将物块A缓慢沿斜面向上拉,直到物块C刚脱离挡板.重力加速度为g,求
(1)未施力前,整个系统处于平衡状态时,物块C对挡板的压力为多少?
(2)当物块C刚脱离挡板时,物块B沿斜面上升的距离为多少?
(3)当物块C刚脱离挡板时,物块A沿斜面上升的距离为多少?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218001897089.jpg)
(1)未施力前,整个系统处于平衡状态时,物块C对挡板的压力为多少?
(2)当物块C刚脱离挡板时,物块B沿斜面上升的距离为多少?
(3)当物块C刚脱离挡板时,物块A沿斜面上升的距离为多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218001897089.jpg)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800189400.gif)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800220830.gif)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218002361457.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800189400.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800220830.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218002361457.gif)
对ABC为研究对象
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800251714.gif)
由牛顿第三定律可得物块C对挡板的压力![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800189400.gif)
初态时:弹簧k1被压缩:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800267588.gif)
弹簧k2被压缩:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800282697.gif)
末态时:弹簧k1被拉伸:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800298721.gif)
弹簧k2被压缩:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800314601.gif)
所以物块B沿斜面上升的距离为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218003291013.gif)
物块A沿斜面上升的距离为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218003451744.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800251714.gif)
由牛顿第三定律可得物块C对挡板的压力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800189400.gif)
初态时:弹簧k1被压缩:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800267588.gif)
弹簧k2被压缩:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800282697.gif)
末态时:弹簧k1被拉伸:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800298721.gif)
弹簧k2被压缩:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121800314601.gif)
所以物块B沿斜面上升的距离为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218003291013.gif)
物块A沿斜面上升的距离为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218003451744.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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