题目内容
一质量为m物块从
粗糙圆弧轨道上顶端A点由静止滑下,圆轨道半径为R,滑至轨道末端B点后进入半径为
的光滑圆轨道,此时速度大小为v,B点切线水平.则物块过B点后瞬间角速度突然增大到原来(B点之前的瞬间) 倍,物块由A滑向B的过程中,摩擦力对物块所做的功 。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241513369622017.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151336697303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151336822447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241513369622017.jpg)
2 ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151337071794.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151337071794.png)
试题分析:物块过B点后运动半径由R瞬间变为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151336822447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151337274454.png)
物块由A滑向B的过程中,用动能定理有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241513373991018.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151337664995.png)
点评:注意此题摩擦力为变力,求变力做功首选用动能定理。
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目