题目内容
如图所示,斜面体置于粗糙水平面上,斜面光滑.小球被轻质细线系住放在斜面上。细线另一端跨过定滑轮,用力拉细线使小球沿斜面缓慢移动一段距离,斜面体始终静止.移动过程中
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012179572658.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012179572658.png)
A.细线对小球的拉力变大 |
B.斜面对小球的支持力变大 |
C.斜面对地面的压力变大 |
D.地面对斜面的摩擦力变大 |
A
试题分析:设物体和斜面的质量分别为m和M,绳子与斜面的夹角为θ.
取球为研究对象:小球受到重力mg、斜面的支持力
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218160382.png)
斜面方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218362830.png)
垂直斜面方向:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012183941013.png)
使小球沿斜面缓慢向上移动时,θ增大,其他量不变,由①式知,F增大.由②知,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218160382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218425463.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218440384.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218456500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218487698.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218160382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218518911.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218160382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001218440384.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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