题目内容
如图所示,建筑装修中,工人用质量为
的磨石对斜壁进行打磨,当对磨石加竖直向上大小为
的推力时,磨石恰好沿斜壁向上匀速运动,已知磨石与斜壁之间的动摩擦因数为μ,则磨石受到的摩擦力是
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250009599121617.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000959772448.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000959881578.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250009599121617.png)
A.(F-mg)cosθ | B.(F-mg)sinθ |
C.μ(F-mg)cosθ | D.μ(F-mg) |
A
试题分析:分析磨石的受力,有重力mg,弹力N(垂直于斜壁向下),摩擦力f(沿斜壁向下),外力F四个力。把这四个力沿斜壁和垂直于斜壁方向正交分解,由于物体处于平衡状态,在沿斜壁方向有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000959959811.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000959975872.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001000006541.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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