Question

A ship sends out ultrasound that returns from the seabed and is detected after 5 s. If the speed of ultrasound through seawater is $1600m{s}^{-1}$, then what is the distance of the seabed from the ship?

• A. 2.5 km
• B. 3.5 km
• C. 4 km
• D. 5 km

Answer 1

The correct option is C

4 km

Let, the distance between ship and seabed be 'd'.

So, the total distance travelled by the sound waves (ship to the seabed and then back to ship) is 2d.

Therefore, $2d=speed\times time$

$\Rightarrow 2d=1600\times 5=8000m$.

$\Rightarrow d=\frac{8000}{2}=4000m=4km$