题目内容
渔船常利用超声波来探测远处鱼群的方位.已知某超声波频率为1.0×105 Hz,某时刻该超声波在水中传播的波动图像如图所示.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018313538.png)
(1)从该时刻开始计时,画出x=7.5×10-3 m处质点做简谐运动的振动图像(至少一个周期).
(2)现测得超声波信号从渔船到鱼群往返一次所用时间为4 s,求鱼群与渔船间的距离(忽略船和鱼群的运动).
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018313538.png)
(1)从该时刻开始计时,画出x=7.5×10-3 m处质点做简谐运动的振动图像(至少一个周期).
(2)现测得超声波信号从渔船到鱼群往返一次所用时间为4 s,求鱼群与渔船间的距离(忽略船和鱼群的运动).
(1)如下图 (2)3 000 m
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018475044.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018475044.jpg)
(1)该波的周期为T=
=1×10-5 s,由波动图像知,此时x=7.5×10-3 m处的质点位于负的最大位移处,所以,从该时刻开始计时,该质点的振动图像如图所示.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018946968.png)
(2)由波形图读出波长λ=15×10-3 m
由波速公式得
v=λf ①
鱼群与渔船的距离为x=
vt ②
联立①②式,代入数据得x=3 000 m ③
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003701863359.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250037018946968.png)
(2)由波形图读出波长λ=15×10-3 m
由波速公式得
v=λf ①
鱼群与渔船的距离为x=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003701909343.png)
联立①②式,代入数据得x=3 000 m ③
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目