题目内容
两个物体A和B,质量分别为2m和m,用跨过定滑轮的轻绳相连,A静止于水平地面上,如图所示,θ=300,不计摩擦,则以下说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043186502877.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043186502877.jpg)
A.绳上拉力大小为mg |
B.物体A对地面的压力大小为![]() |
C.物体A对地面的摩擦力大小为![]() |
D.地面对物体A的摩擦力方向向右 |
AC
试题分析:对B受力分析可知绳上拉力大小等于物体的重力mg,A正确;对A受力分析、正交分解如图所示,根据平衡条件可知:地面对物体A的摩擦力方向向左,D错误;地面对物体A的摩擦力大小等于F的水平分力,即为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004318681657.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004318713590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004318681657.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004318713590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043187753478.jpg)
![](http://thumb2018.1010pic.com/images/loading.gif)
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