题目内容
(10分)如图所示,质量为15kg的物体用两根绳子AO和BO吊挂在天花板下处于静止状态,绳AO、BO与竖直方向的夹角分别为53°、37°。(sin37°=0.6,cos37°=0.8,取g=10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002489773234.jpg)
(1)求两根绳子受到的拉力大小。(6分)
(2)如果绳AO、BO的最大承受力都是200N,为了使绳子不被拉断,则所挂的重物的质量最多不能超过多少?(4分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002489773234.jpg)
(1)求两根绳子受到的拉力大小。(6分)
(2)如果绳AO、BO的最大承受力都是200N,为了使绳子不被拉断,则所挂的重物的质量最多不能超过多少?(4分)
(1)90N、 120N (2)25kg
试题分析:对物体进行受力分析如图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002491334964.jpg)
根据平衡条件:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002491801035.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249336859.png)
整理得;
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249367616.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249445644.png)
(2)由于
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249336859.png)
因此当
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249476641.png)
此时
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249492906.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002491801035.png)
将
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000249476641.png)
物体的质量:m=25kg
![](http://thumb2018.1010pic.com/images/loading.gif)
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