题目内容
一光滑圆球,重量为200N,紧靠墙壁用绳悬挂于O点。已知圆球半径为0.2m,绳长为0.2m,
小题1:求圆球对墙壁的压力和对绳的拉力;
小题2:若绳所能承受的最大拉力为400N,当绳的长度变为多少时,绳被拉断?,
小题1:求圆球对墙壁的压力和对绳的拉力;
小题2:若绳所能承受的最大拉力为400N,当绳的长度变为多少时,绳被拉断?,
小题1:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226319471.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226334477.gif)
小题2:0.03m
(1)绳与墙壁的夹角θ=30°,将重力分解,有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226350710.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226366699.gif)
则圆球对墙壁的压力和对绳的拉力分别为
和![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226334477.gif)
(2)当球对绳的拉力为400N时,绳与墙壁的夹角为α,有
,α=60°
则绳长为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226631864.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226350710.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226366699.gif)
则圆球对墙壁的压力和对绳的拉力分别为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226319471.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226334477.gif)
(2)当球对绳的拉力为400N时,绳与墙壁的夹角为α,有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226444688.gif)
则绳长为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125226631864.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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