Question

The minimum distance to hear an echo is (taking the velocity of sound in air to be 330 m/s)

Answer 1

17 m is the answer
Hope this would help you

Answer 2

Answer:

16.5m

Explanation:

Let the distance from you and the object be x. So for you to hear the echo the sound wave has to travel double the distance to reflect back . As he question suggests the velocity of sound air is 333 m/s. And for a human ear to distinguish two voice there should be atleast 0.1s time duration,, we take t as time and assign it 0.1s. The end equation that we get is:

2x = 333m/s * 0.1

x = 333m/s * 0.05

x = 16.5

Hope it helps you.