题目内容
如图所示,一质量为m的滑块静止置于倾角为30°的粗糙斜面上,一根轻弹簧一端固定在竖直墙上的P点,另一端系在滑块上,弹簧与竖直方向的夹角为30°.则下列说法正确的是 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500215186618799.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500215186618799.png)
A.滑块一定受到四个力作用 |
B.弹簧一定处于压缩状态 |
C.斜面对滑块的支持力大小可能为零 |
D.斜面对滑块的摩擦力大小一定等于![]() |
D
试题分析:有几何关系可知,弹簧轴线与斜面垂直,即弹簧弹力与斜面垂直。对物体受力进行正交分解如下图,沿斜面方向有重力的分力
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002151897584.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250021519131128.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002151929536.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002151944585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002151960415.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500215197512263.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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