题目内容
一列简谐横波在t=0时刻的波形如图中的实线所示,t=0.02s时刻的波形如图中虚线所示。若该波的周期T大于0.02s,则该波的传播速度可能是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430019764464.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430019921733.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430019764464.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430019921733.png)
A.2m/s |
B.3m/s |
C.4m/s |
D.5m/s |
B
(1)设波向右传播,则在0时刻x=4m处的质点往上振动,
设经历
时间时质点运动到波峰的位置,则
,即
。
当n=0时,
,符合要求,此时
;
当
时,
,不符合要求。
(2)设波向左传播,则在0时刻x=4m处的质点往下振动,
设经历
时间时质点运动到波峰的位置,则
,即
。
当n=0时,
,符合要求,此时
;
当
时,
,不符合要求。综上所述,只有B选项正确。
设经历
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002039323.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002085952.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002226999.png)
当n=0时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002273684.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430023191016.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002413364.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002460701.png)
(2)设波向左传播,则在0时刻x=4m处的质点往下振动,
设经历
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002616374.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002694974.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241430027721061.png)
当n=0时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002819821.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002881817.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002413364.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143002975789.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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