Question

A boy receive his account 3 sec later. Find the distance of the reflecting surface from the boy. Speed of the sound Is 324m per sec

Answer 1

we know time =distance/speed
because receive his account 3sec later , it means sound first go and strike fixed surface and then come , hence distance covered by sound is two times distance b/w boy and striking (reflecting) surface .

let distance between boy and reflecting surface=x

time=distance covered by sound /speed of sound
3sec=2x/324
2x=324 x 3=972m
x=486m
hence distance between boy and reflecting surface is 486m