Question

If the splash is heard 4.23 seconds after a stone is dropped into a well 78.4m deep. Find the velocity of sound in air.

Answer 1

ssuming no air (or air drag) on stone, the time it takes stone to reach water is: 
t = √2h/g = √2(78.4)/9.81 = √15.98369 = 3.998 s 
time for sound to travel 78.4 m = 4.23 - 3.998 = 0.232 s 
speed of sound in well = 78.4/0.232 = 338 m/s ANS* 

Answer 2

338 m/s is the answer to the question