题目内容
做圆周运动的两个物体M和N,它们所受的向心力F与轨道半径R之间的关系如图所示,其中图线N为双曲线的一个分支.则由图象可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241458124261887.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241458124261887.jpg)
A.物体M和N的线速度均保持不变 |
B.在两图线的交点,M和N的动能相同 |
C.在两图线的交点, M和N的向心加速度大小相同 |
D.随着半径增大,M的线速度增大,N的角速度减小 |
BD
试题分析:A、物体M的向心力F与轨道半径R之间的关系满足
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812442639.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812489675.png)
B、在两图线的交点表示F和R相同,由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812489675.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812629818.png)
C、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812723566.png)
D、由于M的角速度不变,由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812785470.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145812832529.png)
故选BD
点评:中等难度。向心力有多种表达形式,如
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241458128941797.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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