A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g = 10 m s–2 and speed of sound = 340 m s–1 .

Height of the tower, s = 500 m

Velocity of sound, v = 340 m/s

Acceleration due to gravity, g = 10 m/s2

Initial velocity of the stone, u = 0 (since the stone is initially at rest)

Time taken by the stone to fall to the base of the tower, t1

According to the second equation of motion:

S = ut1 + 1/2gt1t1

500 = 0 x t1 + 1/2 x 10 x t1t1

t1 t1 = 100

t1 = 10s

Now, the time is taken by the sound to reach the top from the base of the tower, t2= 500/340 = 1.47 s

Therefore, the splash is heard at the top after time, t

Where, t= t1 + t2 = 10 + 1.47 = 11.47 s.