题目内容
如图所示,物体A、B的质量均为m,通过定滑轮用细绳相连,细绳的OB段竖直、OA段水平,设物体A与接触面间的动摩擦因数为
,其他摩擦不计.则:欲使物体A在水平面上做匀速直线运动,水平施于物体A的力F应为多大?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506495051080.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649443301.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506495051080.png)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649692703.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649630712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649692703.png)
试题分析:(1)当A向右匀速运动时,其所受滑动摩擦力水平向左
对B:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649801656.png)
对A:竖直方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649864600.png)
水平方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649973596.png)
其中:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150650082597.png)
代入数据,解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649630712.png)
(2)当A向左匀速运动时,其所受滑动摩擦力水平向左
对A:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506502851236.png)
代入数据,解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150649692703.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506504251123.png)
点评:做本体的关键是根据运动情况分析物体受力,然后结合力的平衡条件列等式
![](http://thumb2018.1010pic.com/images/loading.gif)
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