15.2 A stone dropped from the top of a tower of height 300 m splashes into the water of a pond near the base of the tower. When is the splash heard at the top given that the speed of sound in air is 340 m/secg=9.8 m/s2

It is given in the question that:
Height of the tower, s = 300 m
Acceleration, a = g = 9.8 m/s2
Speed of sound in air = 340 m/s
If the time taken by the stone to strike the water in the pond=t1
Using the second equation of motion:
Time taken by the sound to reach the top of the tower, t2=300340=0.88 s
Therefore, the time after which the splash is heard, 
= 7.82 + 0.88 = 8.7 s