Question

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

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

Answer 1

The correct option is C

$4km$

Given:
Speed of ultrasound in seawater, $v=1600m{s}^{-1}$
Time for sound to travel from ship to seabed and then back, $t=5s$

Let the distance between ship and seabed be $d$.

The total distance travelled by the sound waves will be $2d$.
Distance travelled by the wave is the product of speed and time.
$2d=vt=1600\times 5=8000m$
$d=\frac{8000}{2}=4000m=4km$
Hence, the distance of seabed from ship is $4km$