题目内容
在验证平四边形定则的实验中,用A、B两个弹簧秤拉橡皮条的结点,使其位于O处,如图所示,此时
,现在保持A读数不变化,减小
角,要使结点仍在O处,可采用的办法是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002381042287.jpg)
A.增大B的读数,同时减小
角
B.增大B的读数,同时增大
角
C.减小B的读数,同时减小
角
D.减小B的读数,同时增大
角
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238073283.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238088205.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002381042287.jpg)
A.增大B的读数,同时减小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238119214.png)
B.增大B的读数,同时增大
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238119214.png)
C.减小B的读数,同时减小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238119214.png)
D.减小B的读数,同时增大
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000238119214.png)
C
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500023819720699.png)
试题分析:要保证结点不动,即保证合力不变,则由平行四边形定则作图如下:
由图可知:合力不变,A方向向合力方向靠拢即减小α角,则B的拉力应减小,同时应减小β角;故ABD错误,C正确。
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目