题目内容
(12分)如图所示,质量为m的物体被两根细绳OA、OB挂在小车上,两根细绳与车顶水平面夹角分别为60°和30°。试求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535049323925.jpg)
①若小车静止不动,绳OA拉力 T1和绳OB拉力T2分别为多大?
②若小车以大小为g的加速度向右匀加速运动时,绳OA拉力 T1和绳OB拉力T2分别为多大?
③为使OA绳的拉力恰好为0,则小车向右运动的加速度为多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535049323925.jpg)
①若小车静止不动,绳OA拉力 T1和绳OB拉力T2分别为多大?
②若小车以大小为g的加速度向右匀加速运动时,绳OA拉力 T1和绳OB拉力T2分别为多大?
③为使OA绳的拉力恰好为0,则小车向右运动的加速度为多大?
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505010762.png)
②
③![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505337516.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505010762.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505119687.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535052441351.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505337516.png)
试题分析:(1)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535055872406.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505010762.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505119687.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535060392121.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535060701391.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535052441351.png)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535062112184.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153506226794.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153505337516.png)
点评:难度中等,本题考查整体隔离法的应用,物体的加速度与车的加速度相同,以物体为研究对象,把受到的力沿水平方向分解,水平方向上的合外力提供加速度
![](http://thumb2018.1010pic.com/images/loading.gif)
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