# Q.20.  A sonar device on a submarine sends out a signal and receives an echo 5 s later. Calculate the speed of sound in water if the distance of the object from the submarine is 3625 m.

Answers (1)
R Ritika Kankaria

Given the distance of the object is 3625 m from the submarine and the time taken is 5 seconds.

But the time gave includes of both journey downward and upward,

hence the time taken will be half of this time.

$t = \frac{5}{2}sec$

And as $Speed = \frac{Distance}{Time}$

Putting the values in the equation, we get

$Speed = \frac{3625}{\frac{5}{2} } = 1450\ m/s$

Therefore, the speed of sound is 1450 m/s.

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