Question

If an echo is heard after 3 sec, then what is the speed of sound if the distance between the source of sound and reflector is 90 m

Answer 1

Echo is heard after 3s. An echo is heard when the sound waves travel from the source, reflect from a surface and reach back to the source.

So, sound waves have to travel twice the distance.

Total distance = 90 + 90 = 180

Speed of sound = distance/ time

= 180/3 = 60m/s