题目内容
质量为60 kg的体操运动员做“单臂大回环”,用一只手抓住单杠,伸展
身体,以单杠为轴做圆周运动.如图3所示,此过程中,运动员到达最低
点时手臂受的拉力至少约为(忽略空气阻力,g=10 m/s2) ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241413043092471.png)
身体,以单杠为轴做圆周运动.如图3所示,此过程中,运动员到达最低
点时手臂受的拉力至少约为(忽略空气阻力,g=10 m/s2) ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241413043092471.png)
A.600 N | B.2400 N |
C.3000 N | D.3600 N |
C
设运动员的重心到单杠的距离为R,在最低点的最小速度为v,则有
mv2=mg·2R
F-mg=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141304418570.png)
由以上二式联立并代入数据解得F=3000 N.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141304371338.png)
F-mg=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141304418570.png)
由以上二式联立并代入数据解得F=3000 N.
![](http://thumb2018.1010pic.com/images/loading.gif)
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