题目内容
(9分)如图,A与B两滑块叠放在水平面上,已知A与B的重力分别为
,
,A与B间的动摩擦因素
,B与水平面间的动摩擦因素
。在用水平拉力F把B向左匀速拉出的过程中,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241453360883107.jpg)
求:(1)地面对B的摩擦力大小。
(2)拉力F的大小。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145335760595.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145335869632.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145335916500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145335978515.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241453360883107.jpg)
求:(1)地面对B的摩擦力大小。
(2)拉力F的大小。
(1)
(2) ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336181537.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336103543.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336181537.png)
试题分析:(1)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336228622.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336353664.png)
由以上两式代入数据解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336103543.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336524628.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336602570.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336649540.png)
由以上三式代入数据解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336181537.png)
点评:在研究摩擦力的时候首先分析清楚过程中的摩擦力属于动摩擦力还是静摩擦力,动摩擦力根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145336790571.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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