Question

An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the time interval between the sending and receiving of the wave is 1.6 s. What is the depth of the sea, if the velocity of sound in the seawater is 1400 m/s?

• A. 1120 m
• B. 560 m
• C. 112 m
• D. 1400 m

Answer 1

Answer: (A)

Given,

Velocity, $V=1400m/s$

Time $t=1.6s$

Depth of the sea $d=?$

In 1.6 sec, the sound wave travels from the ship to the bottom of the sea and then comes back to the ship because of the reflection by the sea bed. Thus the distance covered by the sound wave is twice the depth of the sea.

$\therefore \text{distance}=2\times \text{the depth of the sea}\left(d\right)$

We know

$\text{Distance}=\text{speed}\times \text{time}$

$\Rightarrow 2d=V\times t$

$\Rightarrow d=\frac{1400\times 1.6}{2}$

$\Rightarrow d=700\times 1.6=1120m$

$\therefore$ option A is correct.