Question

The echo-receiver of a sonar attached to a ship, receives the echo from the bottom of sea 4 seconds after the ultrasonic waves were sent into the sea.
If the speed of sound in water is 1500 m/s, then what is the depth of the sea​

Answer 1

Answer:

Given:

Echo is received after 4 secs.

Speed of sound in water = 1500 m/s

To find :

Depth of the sea

Concept :

Sound emitted from the under-surface of the ship traverses down, reaches the ocean-bed . There it undergoes reflection and travels upward and received by the ship.

So , the sound wave actually travels twice the depth of the ocean bed.

Calculation:

Let ocean bed depth be d .

But total distance travelled = 2d

$\therefore \: 2d = speed \times time$

$= > 2d = 1500 \times 4$

$= > 2d = 6000 \: metres$

$= > d = 3000 \: metres$

So depth of the ocean is 3000 metres.

Importance of Sonar :

• It helps to detect the depth of ocean floor.
• It helps to detect any enemy submarines present near the ship.
• It also helps in locating community of fishes in a particular region.

Answer 2

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Given :

• Time (t) = 4 s
• Speed of sound = 1500 m/s

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To Find :

Depth of the ocean

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Solution :

Let the depth of the ocean be x m. And as we know that in SONAR the echo is first released from the ship, it goes to the depth of the ocean (x) and then comes back again to the source of echo. Which tells us about the depth of the ocean.

So, If depth is x, Then the distance traveled by the echo should be 2x

Now, use formula for speed :

$\large \green {\boxed{\sf{\blue{Speed \: = \: \dfrac{Distance}{Time}}}}} \\ \\ \implies {\sf{Distance \: = \: Speed \: \times \: Time}} \\ \\ \implies {\sf{2x \: = \: 1500 \: \times \: 4}} \\ \\ \implies {\sf{2x \: = \: 6000}} \\ \\ \implies {\sf{x \: = \: \dfrac{6000}{2}}} \\ \\ \implies {\sf{x \: = \: 3000}} \\ \\ \\ {\underline{\sf{\therefore \: \: Depth \: of \: Ocean \: is \: 3000 \: m}}}$

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• Sonar Stands for, Sound Navigation and Ranging .

• It is based on the property of the reflection of the sound waves.

• It is used for measuring depth of oceans, seas.