题目内容
细绳一端系着质量M=8kg的物体,静止在水平面,另一端通过光滑小孔吊着质量m=2kg的物体,M的中点与圆孔的距离r=0.2m,已知M与水平面间的动摩擦因数为0.2,现使此物体M随转台绕中心轴转动,问转台角速度ω在什么范围m会处于静止状态?(g="10" m/s2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752318081410.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752318081410.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752320731227.png)
试题分析:当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175232323399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175232572847.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175232916513.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752331341004.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175232323399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175233664865.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824175232916513.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752342421099.png)
所以:m处于静止状态时转台角速度ω的范围为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241752320731227.png)
点评:该类型题目关键点在找到两个物体直接的联系,本题中两物体靠轻绳连接,绳子上的力相等是关键,其次静摩擦力方向不确定也是需要注意的地方。
![](http://thumb2018.1010pic.com/images/loading.gif)
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