A sonar deivce attached to a ship sends. Ultrasomic waves in the sea. These waves are reflected from the bottom of the sea. If the ultrasonic waves take 4 seconds to travel from the ship to the bottom of the sea and back to the ship (in the form of an echol), what is the depth of the sea? (Speed of sound in water `= 1500 m//s)`.

Explanation

The time taken by the ultrasonic sound waves to travel from the ship to the sea-bed, and back to the ship is 4 seconds. So, the time taken by the ultrasonic sound to travel from the ship to sea-bed will be half of this time, which is `(4)/(2) =2` second. This means that the sound takes 2 seconds to travel from the ship to the bottom of the sea.
Now, Speed `= ("Distance")/("Time")`
So, `1500 = ("Distance")/(2)`
And, Distance `= 1500 xx 2m = 3000m`
Thus, the depth of this sea below the ship is 3000 metres.