题目内容
在“验证力的平行四边形定则”的实验中,若用两根弹簧测力计将一根橡皮筋拉伸至O点,A弹簧测力计拉力方向与PO的延长线成30°角,B弹簧测力计拉力方向与PO的延长线成60°角,如图所示.若A弹簧测力计的读数为FA,B弹簧测力计的读数为FB,此时橡皮筋的弹力为FP,则下列判断正确的是 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018354933601.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018354933601.jpg)
A.FA>FB>FP |
B.FB>FA>FP |
C.FP>FB>FA |
D.FP>FA>FB |
D
试题分析:根据几何知识可得,三个力正好构成一个直角三角形,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001835509663.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001835524717.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001835540752.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001835571586.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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