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.