Question

The deepest recorded point below the sea level is in the Mariana trench, Pacific ocean this point is $11km$ below the sea level. A research vessel sends down a sonar signal to confirm this depth. After how long can it expect to get the echo?Take the speed of sounds in seawater as $1520m/s.$

Answer 1

Step 1: Given data

Distance$d=11kms=11000m$

Speed of the wave $v=1520m/s$

Step 2: Finding the distance of the seabed from the ship

As, $Dis\tan ce=speed\times time$

If $d$ is the distance of the seabed from the ship, the wave travels a distance of $2d.$

So, $$\begin{gathered} 2d=v\times t \\ t=\frac{2d}{v}=\frac{2\times 11000}{1520}=14.66seconds. \end{gathered}$$

Hence, the echo will be heard $14.66seconds$ after it has been sent.