题目内容
已知在单摆a完成10次全振动的时间内,单摆b完成6次全振动,两摆长之差为1.6 m.则两单摆摆长la与lb分别为( )
A.la="2.5" m,lb="0.9" m | B.la="0.9" m,lb="2.5" m |
C.la="2.4" m,lb="4.0" m | D.la="4.0" m,lb="2.4" m |
B
单摆完成一次全振动所需的时间叫单摆的周期,据题设可知a、b两单摆的周期之比为Ta∶Tb=6∶10,由单摆周期公式T=2π
得:
=
,即
=
.据题设lb-la="1.6" m.
联立解得la="0.9" m,lb="2.5" m.选项B正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120513026300.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120513026372.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120513057425.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120513073302.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120513089354.gif)
联立解得la="0.9" m,lb="2.5" m.选项B正确.
![](http://thumb2018.1010pic.com/images/loading.gif)
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