Question
Calculate the minimum distance required for an echo to be heard.
✓
Answer
We know that, speed of the sound in air is $344 m / s$
and minimum time required to hear an echo $=\frac{1}{10} s =0.1 s$
We know,
distance $=$ speed $\times$ time $=344 \times 0.1=34.4 m$
As the sound travels twice between the source and the reflecting surface before an echo is heard, the minimum distance required to hear an echo is $\frac{34.4}{2} m =17.2 m$
and minimum time required to hear an echo $=\frac{1}{10} s =0.1 s$
We know,
distance $=$ speed $\times$ time $=344 \times 0.1=34.4 m$
As the sound travels twice between the source and the reflecting surface before an echo is heard, the minimum distance required to hear an echo is $\frac{34.4}{2} m =17.2 m$
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