physics

The time after which the splash is heard will be the sum of time taken by the ball to reach the water level and time taken by the sound to reach your ear.

 

Let.

Time taken by the ball to reach the water level = t

Time taken by the sound to reach your ear = t'

Time after ehich the splash will be heard = T

Distance travelled by ball = s = h

 

T = t + t'

 

Ball is dropped. Hence the initial velosity of the ball is zero.