题目内容
如图所示,矩形均匀薄板长AC = 60cm,宽CD = 10cm.在B点以细线悬挂,板处于平衡,AB = 35cm,则悬线和板边缘CA的夹角α等于多少?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113828766798.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113828766798.gif)
α= 450
均匀矩形薄板的重心在其对角线AD、CE交点O处,如图 (解)所示,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241138287821085.gif)
根据二力平衡可知重力G与悬线拉力等大反向,且共线.过O作OF交AC于F,由几何关系可知
tanα=
=
=
= 1,
则α= 450.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241138287821085.gif)
根据二力平衡可知重力G与悬线拉力等大反向,且共线.过O作OF交AC于F,由几何关系可知
tanα=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113828797337.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113828813429.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113828813336.gif)
则α= 450.
![](http://thumb2018.1010pic.com/images/loading.gif)
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