On sending an ultrasonic wave from a ship towards the bottom of a sea, the time interval between sending the wave and receiving it back is found to be 1.5 s. If the velocity of the wave in sea water is 1400 ms^-1, find the depth of sea.

As we know,

$\text {Speed of sound (V)} = \dfrac{\text{Total distance travelled (2d)}}{\text {time interval (t)}} \\[0.5em]$

Total distance travelled by the sound in going and then coming back = 2d

Given,

t = 1.5 s

V = 1400 ms^-1

Substituting the values in the formula above, we get,

$1400 = \dfrac{2d}{1.5} \\[0.5em] \Rightarrow d = \dfrac{1400 \times 1.5}{2} \\[0.5em] \Rightarrow d = 700 \times 1.5 \\[0.5em] \Rightarrow d = 1050 m$

Therefore, the depth of the sea = 1050 m