Question

A boy yells in a narrow valley. The sound reflects off of a boulder that is 80 m away. How long will it take to hear the echo if the speed of a sound wave is 320 m/s?

Answer 1

$Given:\\v=320 \frac{m}{s}\\s=2\cdot 80m=160m\\\\Find:\\t=?\\\\Solution:\\\\v= \frac{s}{t} \;\;\;/\cdot t\\\\vt=s\;\;\;/v\\\\t= \frac{s}{v} \\\\t= \frac{160m}{320 \frac{m}{s}} =0.5s$

Answer 2

On Edge-nuity the answer is B.0.50 sec.