question_answer

An observer stands at a distance of 850m from a cliff and fires a gun. After what time gap will he hear the echo, if sound travels at a speed at\[~\text{35}0\text{ m}{{\text{s}}^{-\text{1}}}\] in air?

Answer:

We know, \[d=\frac{v\times t}{2}\]\[\Rightarrow \]\[t=\frac{2\times d}{v}=\frac{2\times 850}{350}=20s\]