题目内容
(8分) 如图所示,长度为L的细绳上端固定在天花板上O点,下端拴着质量为m的小球。当把细绳拉直时,细绳与竖直线的夹角为θ=60°,此时小球静止于光滑的水平面上。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006309652459.png)
(1)当球以角速度
做圆锥摆运动时,水平面受到的压力N是多大?
(2)当球以角速度
做圆锥摆运动时,细绳的张力T为多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006309652459.png)
(1)当球以角速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000630981576.png)
(2)当球以角速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000630981634.png)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631028850.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631012635.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631028850.png)
试题分析:设小球做圆锥摆运动的角速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631043313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631059815.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631075714.png)
由以上二式解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631090746.png)
(1)∵
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631106402.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631121806.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631137813.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631137475.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631012635.png)
(2)∵
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631168408.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631184280.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631199427.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631215289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631231820.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631246691.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631262539.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000631028850.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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