题目内容
如右图所示,重为
的物体A在大小为F、方向为水平向左的恒力作用下,静止在倾角为α的光滑斜面上.现将重为
的小物体B轻放在A上,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242159596021768.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215957262343.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215958729375.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242159596021768.jpg)
A.A仍静止 | B.A将加速下滑 |
C.斜面对A的弹力不变 | D.B对A的压力大小等于![]() |
B
试题分析:不放B时,对A进行受力分析(如右图),由受力平衡得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220000881619.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220001693791.png)
故选B.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242200025822097.jpg)
点评:本题属于共点力平衡的基本问题,关键掌握求解力的方法,比如合成法、分解法、正交分解法等.
![](http://thumb2018.1010pic.com/images/loading.gif)
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