题目内容
五个共点力的情况如图所示。已知
,且这四个力恰好为一个正方形,
是其对角线。下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241520143423031.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014186643.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014264360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241520143423031.png)
A.![]() ![]() ![]() |
B.![]() |
C.除![]() ![]() |
D.这5个力的合力恰好为![]() ![]() ![]() |
AD
试题分析:A、根据力的三角形法则可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014264360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014264360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
B、把
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152015824351.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016073352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016073352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152015824351.png)
C、把
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152015824351.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016073352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016884471.png)
D、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016073352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152015824351.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152016884471.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014264360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014825434.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014825434.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014435335.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152014544365.png)
故选AD
点评:熟练应用平行四边形定则和三角形法则求多个力的合力,知道合力和分力的关系。
![](http://thumb2018.1010pic.com/images/loading.gif)
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