Let ‘s’ be the distance between the man and the mountain and let ‘v’ be the velocity of sound.
Given
: Drumming rate = 50 per minute.
∴ Interval between successive beats
= \(\frac{60}{50}\) = 1.2/sec
Time taken by the echo = 2s/v
Given that when the drumming rate is 50 per minute, echo is not heard by the man
⇒ beats overlap in time frame
i.e., 2s/v = 1.2 .........(2)
Similarly when the person moves 100 m towards the mountain, with drumming rate = 60 per minute
Substituting this in (1) we get.
v = 1000 m/s