题目内容
(16分)如图所示,质量均为
的A、B物块紧靠着在倾角为
粗糙斜面上一起加速下滑,斜面与A之间动摩擦因数为
,与B之间动摩擦因数为
,已知重力加速度为
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017546522778.jpg)
(1)求下滑过程中AB之间作用力的大小;
(2)若改变倾角,使AB刚好匀速运动,求AB之间相互作用力又为多少.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754449338.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754465310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754496415.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754621322.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754637306.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017546522778.jpg)
(1)求下滑过程中AB之间作用力的大小;
(2)若改变倾角,使AB刚好匀速运动,求AB之间相互作用力又为多少.
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017546831043.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754668997.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017546831043.png)
试题分析:(1)A、B两物体受到斜面的支持力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754699890.png)
所受滑动摩擦力分别为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754715666.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754746604.png)
对整体受力分析,由牛顿第二定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754761997.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017547771050.png)
再隔离A物体,进行分析研究得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754808983.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754668997.png)
(2)设倾角为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001754855292.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017548861196.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017549021112.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250017546831043.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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