本题目来源于试卷: Physics Unit12: Sound，类别为 通用国际物理
[单选题]
Sonar is used to deter6ew *3taphb;f.zevq4 minf7 y,lzs+cqq84b s0e jut 0c y;crvb6;e the speed of an object. A 40-kHz signal is sent out, and a 42-kHz signal isce +yr ,btfvb;qjcs u0ls 6;cy74qz80 returned. Assume the speed of sound is 345 m/s. How fast 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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