Question

a stone is dropped into a well 44 m deep and the sound of splash is heard after 3.12sec.find the speed of sound in air.

Answer 1

Given,
Depth of well, h=44 m
Initial velocity of stone, u=0
Time taken by the stone to hit the well is given by
$$\begin{gathered} \mathrm{t}=\sqrt{\frac{2\mathrm{h}}{\mathrm{g}}} \\ =\sqrt{\frac{2\times 44}{9.8}} \\ =\sqrt{\frac{88}{9.8}}=3\sec \left(\mathrm{approx}\right) \\ \mathrm{Now},\mathrm{time}\mathrm{taken}\mathrm{by}\mathrm{sound}\mathrm{to}\mathrm{reflect}\mathrm{back}=\mathrm{Distance}/\mathrm{Speed} \\ \mathrm{or}\mathrm{Speed}=\mathrm{Distance}/\mathrm{time}=44/(3.12-3) \\ =44/0.12=366\mathrm{m}/\mathrm{s}\left(\mathrm{approx}\right) \end{gathered}$$