题目内容
射箭是奥运会比赛项目之一,如右图甲为我国著名选手张娟娟的射箭场景。已知弓的顶部跨度为l,弦均匀且弹性良好,其自由长度为l。发射时弦和箭可等效为右图乙的情景,假设弓的跨度保持不变,即箭在弦的正中间,弦夹住类似动滑轮的附加装置上,将箭发射出去。已知弦的劲度系数为k,发射箭时弦的最大长度为
(弹性限度内),则箭被发射瞬间所受的最大弹力为(设弦的弹力满足胡克定律) ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241301002312979.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130100168399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241301002312979.jpg)
A.![]() |
B.![]() |
C.![]() |
D.![]() |
B
弓弦张力
,弓弦对箭的作用力![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130100589852.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130100543871.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130100589852.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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