A stone is dropped into a well of 80m deep. The sound of splash is heard 4.20 sec after the stone is dropped. Find the velocity of sound in air.

Answer 1

time to fall is from

80 = 4.9t^2
t = 4.04 s

time for sound to return: 4.20-4.04 = 0.16 s

80m/0.16s = 500m/s

Answer 2

The answer is not 500 it is 400