You are standing in the very center of a deep,flat-bottomed valley,and shout "Hello!" If the speed of sound is 343 m/s,and you hear the second echo "Hello!" at 2.1 seconds after you shout,how wide is the valley?
A)360 m
B)180 m
C)720 m
D)540 m

Question

Quizplus · Accepted Answer

The time it takes for the echo to return is 2.1 seconds, which accounts for the sound to travel to the valley wall and back. Therefore, the total distance covered by the sound is $343 \, \text{m/s} \times 2.1 \, \text{s} = 720.3 \, \text{m}$. Since this distance is the round trip for the sound, the width of the valley is half of that, which is $360.15 \, \text{m}$, rounding to $360 \, \text{m}$.

You Are Standing in the Very Center of a Deep,flat-Bottomed