A stone dropped from the top of a tower of height 300 m high 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 340ms−1 ? (g=9.8ms−2)
Height of the tower, s = 300 m
Initial velocity of the stone, u = 0
Acceleration, a=g=9.8m/s2
Speed of sound in air = 340 m/s
The time (t1) taken by the stone to strike the water in the pond can be calculated using the second equation of motion, as:
s=ut1+12gt21300=0+12×9.8×t21∴t1=√300×29.8=7.82s
Time taken by the sound to reach the top of the tower, t2=300340=0.88s
Therefore, the time after which the splash is heard, t=t1+t2
=7.82+0.88=8.7 s