Question

1. Calculate the minimum distance at which a person should stand in front of a reflecting surface to
be able to hear an echo (speed of sound in air = 350 m/s).​

Answer 1

Answer:

Speed of sound in air = 340 m/s

We can only hear the echo if it reflects and comes back after 0.1 second.

2d(because distance from the object + reflected distance) = (340*0.1)m=34m

d= 34/2= 17m

But if you take speed of sound as 350m, the answer will be 17.5m

Hope this helps!