题目内容
如图所示,静止在光滑水平面的木板B的质量
kg、长度L="2.0m." 铁块A静止于木板的右端,其质量
kg,与木板间的动摩擦因数
,并可看作质点。现给木板B施加一个水平向右的恒定拉力
,使木板从铁块下方抽出,试求:(取g=10m/s2)
(1)抽出木板所用的时间;
(2)抽出木板时,铁块和木板的速度大小各为多少?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241227046922193.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704552390.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704583380.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704645272.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704661415.gif)
(1)抽出木板所用的时间;
(2)抽出木板时,铁块和木板的速度大小各为多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241227046922193.jpg)
(1)对铁块有![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704708586.gif)
得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704723559.gif)
对木块有![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704739461.gif)
得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704755808.gif)
抽出木板的过程中:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241227047705506.jpg)
铁块位移![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704786444.gif)
木板位移![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704801465.gif)
两位移之间的关系为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704879280.gif)
即![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704879552.gif)
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704926874.gif)
(2)抽出木板的瞬间,铁块的速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704942625.gif)
木板的速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704957639.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704708586.gif)
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704723559.gif)
对木块有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704739461.gif)
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704755808.gif)
抽出木板的过程中:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241227047705506.jpg)
铁块位移
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704786444.gif)
木板位移
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704801465.gif)
两位移之间的关系为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704879280.gif)
即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704879552.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704926874.gif)
(2)抽出木板的瞬间,铁块的速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704942625.gif)
木板的速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122704957639.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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