题目内容
质量为M的光滑圆槽放在光滑水平面上,一水平恒力F作用在其上促使质量为m的小球静止在圆槽上,如右图所示,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242135261643591.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242135261643591.jpg)
A.小球对圆槽的压力为 |
B.小球对圆槽的压力为 |
C.水平恒力F变大后,如果小球仍静止在圆槽上,小球对圆槽的压力增加 |
D.水平恒力F变大后,如果小球仍静止在圆槽上,小球对圆槽的压力减小 |
C
试题分析:以圆槽与小球组成的系统为研究对象,由牛顿第二定律可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213526928612.png)
解得系统的加速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213527708614.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824213528379749.png)
小球受到圆槽的支持力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242135295021535.png)
小球对圆槽的压力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242135311091260.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242135323101105.png)
故选C.
点评:熟练应用整体法与隔离法是正确解题的关键,应用平行四边形定则、牛顿第二定律、牛顿第三定律即可正确解题.
![](http://thumb2018.1010pic.com/images/loading.gif)
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