题目内容
如图所示,斜面体B静置于水平桌面上.一质量为m的木块A从斜面底端开始以初速度
上滑,然后又返回出发点,此时速度为
,且
.在上述过程中斜面体一直静止不动,以下说法正确的是:( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006250532340.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000624991323.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625006265.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625037394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006250532340.jpg)
A.桌面对B的静摩擦力的大小保持不变 |
B.桌面对B始终有水平向左的静摩擦力 |
C.物体A受到的摩擦力大小不变 |
D.A上滑时比下滑时桌面对B的支持力大 |
BC
试题分析:由于
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625037394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625084790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625115527.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500062513116706.png)
物体B静止,处于平衡条件,由平衡条件得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625147775.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625193885.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625084790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006252251040.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006252561067.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000625271569.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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