题目内容
如图所示,为一简谐横波在介质中沿x轴正方向传播的t=0时刻波形图,已知在tˊ=0.25s时刻,x =1.5m处的质点P第一次出现波谷,那么下列说法正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242109296243511.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242109296243511.jpg)
A.t=0时刻,质点P的位移为10cm |
B.该波波速为6m/s |
C.在tˊ时刻,x =2m处的质点L沿+y方向运动 |
D.x =4m处的质点N的振动方程为y= —20sin5πt(cm) |
D
试题分析:t=0时刻,质点P在最大振幅的下方,故位移大于10cm小于20cm,A错误;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824210930295556.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824210931481960.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824210932495855.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824210933649882.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824210934492717.png)
故选D
点评:本题关键是运用波形的平移法求出波速
![](http://thumb2018.1010pic.com/images/loading.gif)
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