Question

61.A man fired a bullet in front of a mountain and he heard its echo after 2sec.After travelling a distance of 85mtowards the mountain,he fired another bullet and heard its echo after 1.5sec.The velocity of sound and distance between the mountain and the man when the fist bullet was fired are---------

Answer 1

$$\begin{gathered} Visthevelocityofthesound \\ disthedis\tan cebetweentheoriginalpositionandmountain \\ 1stcase: \\ dis\tan cetravel=2d \\ timetaken=2s \\ v=\frac{2d}{2} \\ 2ndcase: \\ dis\tan cetravel=2(d-85) \\ timetaken=1.5s \\ v=\frac{2(d-85)}{1.5} \\ therefore \\ \frac{2(d-85)}{1.5}=\frac{2d}{2} \\ 2d-170=1.5d \\ .5d=170 \\ d=340m \\ v=340m/s \end{gathered}$$