Question

A man fires a gun towards a hill and hears its echo after `5 s`. He then moves `340 m` towards the hill and fires his gun again. This time he hears the echo after `3 s`. Calculate the speed of sound.

Answer 1

Correct Answer - 340 m//s
Here, `t_1 = 5 s, t_2 = 3 s`
As `d = (vt)/(2), v = (2d)/(t)`
In the first case, `v = (2 d)/(t_1) = (2d)/(5)` …(i)
In the second case, `v = (2(d - 340))/(t_2) = (2(d - 340))/(3)`…(ii)
From eqns. (i) and (ii), `(2d)/(5) = (2(d - 340))/(3)` or `3d = 5d - 1700` or `d = 850 m`
From eqn. (i), `v = (2 xx 850)/(5) = 340 m//s`.