Question

A body is dropped into a deep well and the sound of splash is heard after 4.23s. If the depth of the well is 78.4m, the velocity of sound in air is (nearly)

• A. 330 m/s
• B. 341 m/s
• C. 380 m/s
• D. 540 m/s

Answer 1

Answer: (B)

341 m/s

It will take $\sqrt{2h/g}$ time to fall and $h/V$ time for sound to be heard, where $V$ is the velocity of sound.
So, the time taken to hear the splash is $t=\sqrt{\frac{2h}{g}}+\frac{h}{V}$
The total time $t$ is 4.23s and $h$ is 78.4m. Substitute these values in the above equation to calculate $V$.