题目内容
如图所示,A、B两球完全相同,质量均为m,用两根等长的细线,悬挂在升降机的天花板上的O点,两球之间连着一根劲度系数为k的轻质弹簧。当升降机以加速度a竖直向上加速运动时,两根细线之间的夹角为θ。则弹簧的长度与原长相比缩短了
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235060783567.png)
A.
B.
C.
D.![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235063271110.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235060783567.png)
A.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123506125926.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123506140734.png)
C.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235062181068.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235063271110.png)
C
对A进行受力分析可知,小球受重力、绳子拉力、弹簧弹力,水平方向的平衡方程为:
,竖直方向:
,计算可得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235066861138.png)
则弹簧的长度与原长相比缩短了x=
,所以选C
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123506655699.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123506671908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235066861138.png)
则弹簧的长度与原长相比缩短了x=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241235062181068.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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