题目内容
如右图所示,在小车中悬挂一小球,若偏角θ未知,而已知摆球的质量为m,小球随小车水平向左运动的加速度为
(取
),则绳的张力为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242154169632840.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215415107462.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215416246625.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242154169632840.jpg)
A.![]() | B.![]() | C.20m | D.(![]() |
A
试题分析:小球受重力mg和绳的拉力FT两个力的作用,受力情况如图所示.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242154208792531.jpg)
根据平行四边形定则,重力mg和绳的拉力FT的合力F的方向水平向左,由牛顿第二定律有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215421659695.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215422922816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824215424139681.png)
点评:解决本题的关键知道小球与车具有相同的加速度,根据牛顿第二定律,通过平行四边形定则进行求解.
![](http://thumb2018.1010pic.com/images/loading.gif)
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