题目内容
质量为m的物块,沿着半径为R的半球形金属壳内壁滑下,半球形金属壳竖直固定放置,开口向上,滑到最低点时速度大小为V,若物体与球壳之间的摩擦因数为μ,则物体在最低点时,下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241727517244070.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241727517244070.jpg)
A.受到向心力为![]() |
B.受到的摩擦力为 ![]() |
C.受到的摩擦力为μ(![]() |
D.受到的合力方向斜向左上方. |
CD
试题分析:根据牛顿第二定律得知,物体在最低点时的向心力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172752379853.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172753331845.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172753581871.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241727538151036.png)
点评:本题是变速圆周运动动力学问题,关键是分析小球的受力情况,确定向心力的来源.对于变速圆周运动,由指向圆心的合力提供向心力.
![](http://thumb2018.1010pic.com/images/loading.gif)
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