题目内容
如图所示两个物体A. B的质量均为1kg,各接触面间的动摩擦因数均为0.3,同时用F=1N的两个水平力分别作用在A. B上,则地面对物体B. B对物体A的摩擦力分别为( )(g=10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161350428856.png)
A. 6N. 3N B. 1N. 1N
C. 0. 2N D. 0. 1N
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161350428856.png)
A. 6N. 3N B. 1N. 1N
C. 0. 2N D. 0. 1N
D
试题分析:对物体A进行受力分析,物体A受到竖直向下的重力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161350615377.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161350864382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161351036355.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241613514266156.jpg)
由共点力平衡可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161351442635.png)
把物体AB看做一个整体进行受力分析.受到竖直向下的重力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161351613432.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824161351754421.png)
物体AB在这四个共点力作用下合外力为零.所以受到地面的摩擦力为0N.选项ABC错误,选项D正确.
故选D.
点评:,常用的方法有整体法和隔离体法.在对物体进行受力分析时,要做到不漏掉力和不随意添加一些力.
![](http://thumb2018.1010pic.com/images/loading.gif)
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