A man clapping his hands at regular intervals observes that the echo of a clap coincides with the next clap. If the reflecting cliff is \(160 m\) away and the speed of the sound is \(320 mS ^{-1}\), what is the frequency of the clapping?
A. 2 HzK B. 4 Hz C. 8 Hz D. 1 Hz E. 12 Hz
Correct Answer: D
Explanation
\(\lambda=160 m , V =320 m / s\) The echo travels: distance \(\times 2=2 \lambda\) and \(v=2 f \lambda\) \begin{array} 320=2 \times f \times 160 \text { thus } f=\underline{320}=1 Hz =D \\ 2 \times 160 \end{array}
