Q. A stone is dropped in a well which is $19.6m$ deep. Echo sound is heard after $2.06\ sec$ (after dropping) then the velocity of sound is
A) $332.6\ m/sec$
B) $326.7\ m/sec$
C) $300.4\ m/sec$
D) $290.5\ m/sec$
Explanation
(b) $t = \sqrt{\frac{2h}{g}} + \frac{h}{v} = \sqrt{\frac{2 \times 19.6}{9.8}} + \frac{19.6}{v} = 2.06$
$\Rightarrow v = 326.7\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.