You are standing in the very center of a deep,flat-bottomed valley,and shout "Hello!" If the valley is 355 m wide,and the speed of sound is 343 m/s,when do you hear the first echo "Hello!"?
A)1.03 s
B)0.517 s
C)1.93 s
D)0.966 s

Question

Quizplus · Accepted Answer

To hear the first echo, the sound must travel to the valley wall and back, covering a distance of 2 * 355 m = 710 m. With the speed of sound at 343 m/s, the time taken is 710 m / 343 m/s = 2.07 s. However, since you're in the very center, the sound only needs to travel half this distance (355 m) to reach a wall and return, taking 1.03 s.

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