Sonic vibrations were sent down from a ship return after 2 seconds. What is the depth of the sea, if the speed of sound in water is 1.5 km s^-1 ?

Speed of sound in water is, v = 1.5 km/s

Sound returns to the ship in 2 s. Means the sound reaches the sea bed in 1 s.

So, depth of the sea is = (1.5)(1) = 1.5 km