Question

15. A man standing between two cliffs fires a gun and
hears an echo every second. The distance of the
man from the nearest cliff is 170 m. Calculate the:
(a) speed of sound and

(b) distance between the cliffs.
​

Answer 1

Let the distance between the second cliff and the man be D.

As we know, speed = distance/time

For 1st cliff and man: He hears the echo every seconds, it means that the sound takes 1 seconds to go and return, it taken 1/2 = 0.5 seconds to cover that distance.

⇒ speed = distance/time

                = 170/0.5

                =  340 m/s    

 For 2nd cliff and man: as this cliff a little far from the man it is heard in the 2nd second. it means that the sound takes 2 seconds to go and return, it taken 2/2 = 1 seconds to cover that distance.

⇒ speed = distance/time

⇒ 340 = D/1

⇒ 340*1 = D     ⇒ 340 = d

 Distance b/w the cliff = 340 + 170

                                     = 510  m