题目内容
如图示,倾角为
的斜面体固定在水平面上,质量为
的方形物块放在斜面上保持静止,已知当地的重力加速度为
。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509051472108.jpg)
(1)斜面对物块的支持力和摩擦力的大小。(8分)
(2)若对物块施加一个水平向右的作用力
,使斜面对物块的摩擦力刚好为零。这个作用力多大?此时斜面对物块的支持力变为多大?(8分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150904929297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150904991337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905054269.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509051472108.jpg)
(1)斜面对物块的支持力和摩擦力的大小。(8分)
(2)若对物块施加一个水平向右的作用力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905194292.png)
(1)
,
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509056151051.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905475587.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905537635.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509056151051.png)
试题分析:(1)物体受到重力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905678402.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905740377.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905865276.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905927599.png)
支持力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150906068944.png)
摩擦力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150906146890.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509062085463.jpg)
(2)物体受到重力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905678402.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150906286406.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150906567302.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150905927599.png)
水平力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150906707871.png)
支持力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509056151051.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509071605228.jpg)
点评:先对物体进行受力分析,然后根据力的平衡条件列式子求解
![](http://thumb2018.1010pic.com/images/loading.gif)
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