题目内容
如图,质量为m1的物体甲通过三段轻绳悬挂,三段轻绳的结点为O,轻绳OB水平且B端与放置在水平面上的质量为m2的物体乙相连,轻绳OA与竖直方向的夹角为37°,物体甲,乙均处于静止状态。(设最大静摩擦力等于滑动摩擦力,g=10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026200937149.jpg)
求:(1)轻绳OA,OB受到的拉力是多大?
(2)物体乙受到的摩擦力是多大?方向如何?
(3)若物体乙的质量m2=4kg,物体乙与水平面间的动摩擦因数为0.3,则欲使物体乙在水平面上不滑动,物体甲的质量m1最大不能超过多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026200937149.jpg)
求:(1)轻绳OA,OB受到的拉力是多大?
(2)物体乙受到的摩擦力是多大?方向如何?
(3)若物体乙的质量m2=4kg,物体乙与水平面间的动摩擦因数为0.3,则欲使物体乙在水平面上不滑动,物体甲的质量m1最大不能超过多少?
(1)
,
(2)
,水平向左(3)1.6 kg.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002620109595.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002620140615.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002620140615.png)
试题分析:(1)对O点受力分析,如图所示,
根据共点力平衡条件可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026201711076.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026202021073.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026202803066.jpg)
(2)乙物体受到OB的拉力和静摩擦力处于静止状态,所以二力大小相等,方向相反,故
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002620312933.png)
(3)刚要发生滑动时,滑动摩擦力
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026203431206.png)
所以当
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250026203741223.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002620390641.png)
即物体甲的质量m1最大不能超过1.6 kg.
![](http://thumb2018.1010pic.com/images/loading.gif)
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