题目内容
如图所示,质量为M的木块静止在光滑水平面上,质量为m的子弹以水平速度v
射入木块,并留在木块里。已知在子弹射入木块的过程中子弹发生的位移为s
,木块发生的位移为s
,子弹进入木块深度为s,子弹受到阻力大小恒为f,子弹射入木块后二者的共同速度为v
,不计空气阻力影响,下列说法中不正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208032814079.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220758539226.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220759677195.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220800894240.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220802127200.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208032814079.jpg)
A.![]() | B.![]() |
C.![]() | D.![]() |
D
试题分析:动能定理告诉我们合外力做功等于动能变化量,功的计算公式中的位移都是相对地面的位移。对子弹有阻力做负功
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220806760904.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220807165866.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208075871353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220808710470.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208092401158.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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