Question

2. A sailor strikes the side of his ship just below the waterline. He hears the
echo of the sound reflected from the ocean floor directly below 2.02 s later
How deep is the ocean at this point? (Speed of sound in water=1500m/s)

Answer 1

Answer:

Given:

Speed of sound in water = 1500 m/s

Time after which the echo is heard is 2.02 seconds.

To find:

Depth of the ocean.

Concept:

When the sailor strikes the side of the boat below the waterline , it actually generates a longitudinal pressure wave (simply Sound wave) . The sound wave travels downwards to reach the ocean floor. After that it undergoes reflection and travels upwards . Finally it reaches the ship at the same position of its origin.

Diagram:

See the attached photo to understand better.

Calculation:

Let ocean depth be d ,

Since the sound wave travels up and down , it actually travels 2d distance.

$\therefore \: distance = speed \times time$

$= > 2d = 1500 \times 2.02$

$= > d = \dfrac{(1500 \times 2.02)}{2}$

$= > d = 1500 \times 1.01$

$= > d = 1515 \: metres$

So final answer :

$\boxed{ \red{depth = 1515 \: m}}$

Additional Information :

• This concept is used by Sonar located underneath the Ships.
• This helps in locating underwater enemy submarines.
• It helps to locate colonies of fishes in a particular area.