Question

A loud sound is made in front of a tall building. An echo is heard 4 seconds after the sound is produced. If the speed of sound in air is 320m/s, how far away is the building?

Answer 1

Speed is distance/time: so if an echo is heard after 4 seconds it had to travel 2x distance(x is the distance between the source and the building) so :

Speed = distance/Time ; D = S/T:

(Answer would be 40 m)