题目内容
(16分)如图所示,一质量为0.99kg的木块静止在水平轨道AB的B端,水平轨道与半径为10m的光滑弧形轨道BC相切。现有一质量为10g的子弹以500m/s的水平速度从左边射入木块且未穿出。已知木块与水平轨道的动摩擦因数μ=0.5,g=10m/s2。求:
(1)子弹射入木块与木块获得的共同速率;
(2)子弹射入后与木块在圆弧轨道上升的最大高度;
(3)从木块返回B点到静止在水平面上,摩擦阻力的冲量的大小。
(1)子弹射入木块与木块获得的共同速率;
(2)子弹射入后与木块在圆弧轨道上升的最大高度;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412104176685.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210417973263.jpg)
(1)
m/s
(2)
m
(3)I = 5N·S
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121041812222.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121041953386.gif)
(3)I = 5N·S
(1)(5分)设子弹射入木块与木块获得的共同速度为v,子弹射入木块前后系统动量守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121041968550.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121041812222.gif)
(2)(5分)设木块上升最大高度为h,子弹与木块在光滑弧形轨道BC上运动,到达最高点
的过程中系统机械能守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121042031831.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121041953386.gif)
(3)(6分)木块返回B点进入水平轨道上作匀减速运动最终静止,摩擦力的冲量为I,由牛顿第二定律、匀变速运动规律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121042093546.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121042109414.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121042124559.gif)
I =" 5N·S " (1分)
![](http://thumb2018.1010pic.com/images/loading.gif)
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