Question

A splash is heard 3.12s after a stone is dropped into a well 45m deep. The speed of sound in air is $[g=10m{s}^{-2}]$

• A. $330m{s}^{-1}$
• B. $375m{s}^{-1}$
• C. $340m{s}^{-1}$
• D. $346m{s}^{-1}$

Answer 1

The correct option is B $375m{s}^{-1}$

Time taken by stone to reach the water surface $t_1=\sqrt[2]{22h/g}=3s$ put h=45 and $g=10$

So time taken by sound to reach the top of the well $45m$ above the water surface is $t-t_1=3.12-3=0.12s$

So speed of sound in air $distance/time=45/0.12=375m/s$

Option B is correct.