Question

(i) A man standing in front of a vertical cliff fires a gun. He hears the echo
after 3.5 seconds. On moving closer to the cliff by 84 m, he hears the echo
after 3 seconds. Calculate the distance of the cliff from the initial position
of the man.​

Answer 1

Answer:

T1=3.5s

T2=3s

D1=x+84m

D2=x

v=2(x+84)/3.5

=2x+168/3.5

v=2x/3

6x+504=7x

x=504m

Initial position of man is 588m in front of the cliff.

PLS MARK IT BRAINLIEST!

Answer 2

Let the initial position of the man be d metere from the cliff

now, d= vt/2

          = v*3.5/2

         = 35v/20.....................(1)

now when the man goes 84 metre forward now the final distance = d-84 metre

now, d-84=vt/2

        35v/20 - 84 = v*3/2          [ using (1) ]

        35v-1680/20 = 3v/2

        35v-1680/10 = 3v

        35v-1680 = 30v

        35v - 30v = 1680

        5v = 1680

        v= 336

so the velocity of sound is 336m/s^2

 putting value of v in (1) we get,

35*336/20 = 588

so the intial distance of the man from the cliff is 588 metre

Thank You and best of luck for rest of yor ICSE exams.....