题目内容
如图为曲柄压榨机结构示意图,A处作用一水平力F,OB是竖直线.若杆和活塞重力不计,两杆AO与AB的长度相同;当OB的尺寸为200,A到OB的距离为10时,求货物M在此时所受压力为多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250033533525162.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250033533525162.png)
5F
力F的作用效果是对AB、AO两杆产生沿杆方向的压力F1、F2,如图 (a).而F1的作用效果是对M产生水平的推力F′和竖直向下的压力FN(见图 (b)),可得对货物M的压力.由图可得:tanα=
=10
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250033533833413.png)
F1=F2=
而FN=F1sinα
则FN=
sinα=
tanα=5F
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003353368386.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250033533833413.png)
F1=F2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003353399629.png)
则FN=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003353399629.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003353430420.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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