Question

How can you calculate the minimum distance for echo?​

Answer 1

Answer:

A pulse of sound is in memory for 0.1 s . To hear an echo, the time difference should be a minimum of 0.1 second.

Speed of sound at 20 degree C is 343 m/s .

Distance that sound travels in 0.1 s is 34.3 m .

For an echo to be heard , the minimum distance is (1/2) of 34.3 ≈ 17 m

If the time is less than 0.1 s , the first sound being still in memory , we hear a prolonged sound called reverberation sound.

Answer 2

Speed of sound in air = distance/time

344 m/s = distance/0.1s

Therfore, distance = 34.4 m

This is the total distance, hence half of 34.4 m is 17.2 m.