Question

A submarine sends out ultrasound and is detected after $3.425\text{s}$. If the speed of ultrasound in seawater is $1531\text{m/s}$, what is the distance of seabed from the submarine?

• A. $5.2\text{km}$
• B. $2.6\text{km}$
• C. $1.3\text{km}$
• D. $3.9\text{km}$

Answer 1

The correct option is B $2.6\text{km}$

Let us suppose the distance of seabed from the submarine is $d$, then, ultrasound will travel a distance of $2d$ before it is detected.

So,

$v=\frac{2d}{t}$

$\Rightarrow d=\frac{vt}{2}=\frac{1531\times 3.425}{2}=2621.8\text{m}=2.6\text{km}$