题目内容
如图3所示,竖直平面内固定一个半径为
的
光滑圆形轨道
,底端
切线方向连接光滑水平面,
处固定竖直档板,
间的水平距离为
,质量为
的物块从
点由静止释放沿轨道滑动,设物块每次与档板碰后速度大小都是碰前的
,碰撞时间忽略不计,则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142369631082.gif)
小题1:物块第二次与档板碰后沿圆形轨道上升的最大高度为多少?
小题2:物块第二次与档板碰撞到第四次与档板碰撞间隔的时间?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236682204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236697221.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236697235.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236713206.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236744205.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236760241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236775203.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236791204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236791200.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236900220.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142369631082.gif)
小题1:物块第二次与档板碰后沿圆形轨道上升的最大高度为多少?
小题2:物块第二次与档板碰撞到第四次与档板碰撞间隔的时间?
小题1:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236978498.gif)
小题2:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142370091026.gif)
小题1:物块在光滑轨道上滑动过程机械能守恒,第一次下滑到底端
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236713206.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237072457.gif)
由于每次与档板碰后速度大小都是碰前的
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236900220.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237134255.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237150507.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237165639.gif)
由①、②得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236978498.gif)
小题2:物块第二次与档板碰后沿圆形轨道上升的最大高度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237212317.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114236682204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237337571.gif)
第二次与档板碰后速度:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237353575.gif)
则第二次与档板碰撞到第三次与档板碰撞间隔的时间为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142373531101.gif)
第三次与档板碰后速度:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114237368492.gif)
则第三次与档板碰撞到第四次与档板碰撞间隔的时间为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142373841107.gif)
因此第二次与档板碰撞到第四次与档板碰撞间隔的时间为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142370091026.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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