题目内容
如图所示,质量为m的物体放在水平桌面上,在与水平方向成θ的拉力F作用下加速向前运动,已知物体与桌面间的动摩擦因数为μ,则下列判断正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241317502851583.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241317502851583.png)
A.物体受到的摩擦力为Fcosθ |
B.物体受到的摩擦力为μmg |
C.物体对地面的压力为mg |
D.物体受到地面的的支持力为mg-Fsinθ |
D
对物体受力分析如图:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241317503483124.png)
水平方向:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131750379765.png)
竖直方向:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131750956840.png)
解得:N=mg-Fsinθ,
,且![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131751003613.png)
可见,只有D正确。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241317503483124.png)
水平方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131750379765.png)
竖直方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131750956840.png)
解得:N=mg-Fsinθ,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241317509871047.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824131751003613.png)
可见,只有D正确。
![](http://thumb2018.1010pic.com/images/loading.gif)
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