Question

A man standing in front of a wall produces a sound and hears an echo after 3s.
He walks ‘x’ m away from the wall and produces the same sound. Now he hears an echo after 5.25s. Calculate the distance he walked away from the wall. (Speed of sound in air is 340 m/s)

Answer 1

v=s/t
340=s/5.25
s=340×5.25
=1785m

Answer 2

As we know that distance=speed into time.
Initially the time will be 3÷2= 1.5 seconds.
Therefore the distance is 1.5 × 340 = 510 metres.
In the second case the echo is heard after 5.25 seconds. Therefore the time taken is 5.25÷2=2.625 seconds.
The distance now is 340×2.265 = 770.1 m
Therefore distance moved is 770.1 metres.