If `d` is the distance of the underwater cliff from the submarine, distance travelled by sonar pulse while going from the submarine and returning to it after getting reflected from the cliff `= 2 d`
Here, time taken by sonar pulse to return, `t = 1.02 s`
speed of sound in water, `v = 1531 m//s`
As total distance travelled by the sonar pulse = speed of sound xx time,
`2 d = v t`
or `d = (vt)/(2)`
i.e., `d = (1531 xx 1.02)/(0.2) = 780.81 m`.
