题目内容
如图,原长分别为L1和L2,劲度系数分别为k1和k2的轻质弹簧竖直地悬挂在天花板上,两弹簧之间有一质量为m1的物体,最下端挂着质量为m2的另一物体,整个装置处于静止状态.现用一个质量为m的平板把下面的物体竖直地缓慢地向上托起,直到两个弹簧的总长度等于两弹簧原长之和,求
(1)m2上升的高度是多少?
(2)此时平板受到人对其的托力为多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241136212671216.gif)
(2)此时平板受到人对其的托力为多大?
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621330994.gif)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621345910.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621330994.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621345910.gif)
(1)挂上重物后,设上面的弹簧伸长x1,下面的弹簧伸长x2
对m1、m2所组成的整体,有:
对m2有
平板把m2托起后,m2上升的高度为
(2)用力托起后,上面的弹簧必伸长,下面的弹簧必缩短,设形变量为x,人对m的托力为F,
对m1、m2、m所组成的整体,有
对m1有
联立解出
或![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621345910.gif)
对m1、m2所组成的整体,有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621392567.gif)
对m2有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621408458.gif)
平板把m2托起后,m2上升的高度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621330994.gif)
(2)用力托起后,上面的弹簧必伸长,下面的弹簧必缩短,设形变量为x,人对m的托力为F,
对m1、m2、m所组成的整体,有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621673729.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082411362168873.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621704575.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082411362168873.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621798974.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113621345910.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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