A submarine emits a sonar pulse, which returns from an underwater cliff in `1.02 s`. If the speed of sound in water is `1531 m//s`, how far away is the cliff ?

Explanation

Here the time taken by the sonar pulse (or ultrasound) to go from the submarine to the underwater cliff and return to the submarine is 1.02 seconds. So, the time taken by the sonar pulse (or ultrasound) to go from the submarine to clift will be half of this time, which is `(1.02)/(2)=0.51` second. Now, knowing the speed of sound in water, we can calculate the distance travelled by sound in 0.51 second. This will give us the distance of the cliff from the submarine.
We know that: Speed `= ("Distance")/("Time")`
So, `1531 = ("Distance")/(0.51)`
And, Distance `= 1531 xx 0.51 = 780.8m`