Question

A stone is dropped from the top of a tower
750 m high into a pond of water at the base of
the tower. Calculate the number of seconds for
the splash to be heard?
Given g = 10 ms and speed of sound =
310ms​

Answer 1

Answer:

14.66 seconds

Explanation:

The time taken for the stone to reach the ground:

s = ut + 1/2 at²

750 = 0(t) + 1/2 x 10 x t²

750 = 5t²

Thus, t² = 150

∴ t =  12.24 seconds

Thus, after 12.24 seconds, the stone will splash into the water

For the sound to reach the observer, it would have to travel 750m upwards again from the pond.

The time taken for the sound to reach the observer from the pond:

750 ÷ 310 = 2.42 seconds

The time after which the observer hears the splash is = Time taken for the stone to reach the ground + Time taken for the sound to reach the observer

Thus,

Time after which splash is heard = 12.24+2.42

∴ Time after which splash is heard = 14.66 seconds

Hence, the splash is heard after 14.66 seconds