题目内容
如图所示,实线为某一时刻一列横波的波形图,虚线为其经0.5 s后的波形图。设该波周期T<0.5s
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241331458233185.png)
(1)若波向左传播,波速为多少?
(2)若波向右传播,波速为多少?
(3)若波速为1.8m/s,则波的传播方向如何?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241331458233185.png)
(1)若波向左传播,波速为多少?
(2)若波向右传播,波速为多少?
(3)若波速为1.8m/s,则波的传播方向如何?
(1)
=0.12(4n+1)m/s n=1、2、3……
(2)
=0.12(4n+3)m/s n=1、2、3……
(3)波向右传播
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133145885569.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133145885569.png)
(3)波向右传播
由图可知:λ=24cm
⑴若波向左传播,则有:0.5s=(n+
)T1 1
又∵T<0.5s
∴
s n=1、2、3……
∴
=0.12(4n+1)m/s n=1、2、3……2
⑵若波向右传播,则有:0.5s=(n+
)T1 3
又∵T<0.5s
∴
s n=1、2、3……
∴
=0.12(4n+3)m/s n=1、2、3……4
⑶若波速为1.8m/s,代入2得:
0.12(4n+1)=1.8![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146431223.png)
非自然数,所以波向右传播
⑴若波向左传播,则有:0.5s=(n+
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133145995303.png)
又∵T<0.5s
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146041656.png)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133145885569.png)
⑵若波向右传播,则有:0.5s=(n+
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146151385.png)
又∵T<0.5s
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146213696.png)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133145885569.png)
⑶若波速为1.8m/s,代入2得:
0.12(4n+1)=1.8
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146431223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133146478519.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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