Question

Prove that to hear a distinct echo, the distance between observer and reflecting surface should be at least 17.2 m at temperature

Answer 1

Yes, that's true.

We know that,

the velocity of sound at STP = 344 m/s

and to hear an echo the sound must cover twice its distance. Let the distance = x m total distance = 2x m.

but,

v = s/t.

The sound goes and comes back to the listener in 0.1 seconds.

We get

344 = 2x / 0.1

2x = 34.4

x = 17.2