本题目来源于试卷: Physics Unit12: Sound，类别为 国际高中通用物理
[单选题]
Sonar is used to deteqe (-j hl8o,dhr)j2efrlrkjn6jk+ kz0; ,nb ;vzdc/ .k mine the speed of an object. A 40-kHz signal is sent out, and a 42-kHz signal is returned. Assume the speed of sound is 345 m/s. How fak.rk;d)vnkl n,jcfz;+ekz 0b26 / jrjst is the object moving?
A. 6.9 m/s
B. 8.4 m/s
C. 331 m/s
D. 347 m/s
参考答案: B
本题详细解析:
暂无
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