题目内容
如图所示,圆心在O点、半径为R的光滑圆弧轨道ABC竖直固定在水平桌面上,OC与OA的夹角为60°,轨道最低点A与桌面相切. 一足够长的轻绳两端分别系着质量为m1和m2的两小球(均可视为质点),挂在圆弧轨道光滑边缘C的两边,开始时m1位于C点,然后从静止释放。则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241547444812961.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241547444812961.jpg)
A.在m1由C点下滑到A点的过程中两球速度大小始终相等 |
B.在m1由C点下滑到A点的过程中重力对m1做功的功率先增大后减少 |
C.若m1恰好能沿圆弧下滑到A点,则m1=2m2 |
D.若m1恰好能沿圆弧下滑到A点,则m1=3m2 |
BC
试题分析:首先这个运动过程相当于是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154744481362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154744731386.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154744481362.png)
此时的绳子与圆的切线是不重合的,而是类似于圆的一根弦线而存在的,所以此时两个物体的速度必然不相同的,A错误,重力的功率就是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154745168501.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154744481362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154744481362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241547454481109.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154745589521.png)
点评:本题的综合性强,有点难度,关键是理解两球的运动性质,以及利用机械能守恒条件分析解题
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目