Question

A submarine is inside the water. It releases a soundwave in order to find any underwater cliff/Hill etc. They heard the echo of the sound wave after 4 seconds and again after 6 seconds from other side . Find the distance between the two cliffs.
Take speed of sound in water as 1500m/s

Answer 1

Given :

• Time taken for first echo = 4 seconds
• time taken for second echo =6 seconds
• speed of sound in water = 1500 m/s

To Find :

• Distance between the first cliff and second cliff

Formula To Be used :

We will use the formula of travelling of sound waves :

• D = s×t

where, D = distance travelled by sound

s = speed of sound

T = time taken

Solution :

As Given, The echo from the first cliff came after 4 seconds.

so, the sound took 2seconds to travell till the cliff.

So, distance between cliff and submarine:

$\displaystyle \rm \implies d = st$

$\displaystyle \rm \implies d = 1500 \times 2$

$\displaystyle \rm \implies d = 3000 m$

So, distance between first cliff and submarine = 3000m

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Now, the echo from the second cliff came after 6 seconds

so, the sound took 3 seconds to travell till the cliff.

So, the distance between cliff and submarine:

$\displaystyle \rm \implies d = st$

$\displaystyle \rm \implies d = 1500 \times 3$

$\displaystyle \rm \implies d = 4500$

so, distance between between second cliff and submarine = 4500m

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so, as it is not given that whether the cliffs are in straight line or not, so I will take it as straight line.

So, distance between two cliffs = 4500m+3000

or, distance = 7500m

Hence, your answer is 7500m