• qais
  • Content Quality

This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
As we know that the perception of a sound usually endures in memory for only 0.1 seconds
so, minimum time for echo = 0.1 sec
distance = d
sound have to travel, from listener to reflector then to listener
so total distance travelled = 2d
now, distance = speed
× time = 340 ×0.1
⇒2d = 34
⇒d = 17 m
minimum distance for echo is 17 m
1 5 1
Okay lets get our facts straight...

Our ears have a time limit before they can switch between sounds 

That is 0.1 seconds....Now the speed of sound in air is about 344  \frac{m}{s}

So the Distance covered will Be

s*d = 34.4 m

But remember an echo has to get reflected so it must travel twice a given distance.


2D = 34.4

D = 17.2

Now we get that the minimum distance for echo is 17.2 m