# A sonar device on a submarine sends out a signal and receives an echo 5 s later.

Question.
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.

Solution:

Time taken between transmission and reception of signal = 5 sec.

Distance of the object from the sub marine = 3625 m.

Speed of sound in water $=\frac{\text { Distance travelled }}{\text { Time taken }}=\frac{7250}{5}=1450 \mathrm{~m} / \mathrm{sec}$