题目内容
如图所示,物体A的质量m="3" kg,用两根轻绳B、C连接于竖直墙上,要使两绳都能绷直,即物体A在如图所示位置保持平衡,现施加一个力F作用于物体,力F的方向如图所示,若夹角
=600,求力F的大小应满足的条件.(取g="10" m/s2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241222529542580.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122252923220.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241222529542580.jpg)
17.3 N≤F≤34.6 N
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241222529702074.jpg)
A球受力如图所示,则有水平方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122252986427.gif)
竖直方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122253001433.gif)
由②式得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122253017711.gif)
由①、②式得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122253032699.gif)
所以力F大小应满足的条件是17.3 N≤F≤34.6 N.
![](http://thumb2018.1010pic.com/images/loading.gif)
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