What is $SONAR$?

$A$ continuous disturbance is created on the surface of water in a ripple tank with a small piece of cork floating on it. Describe the motion of the cork. What does this tell us about the disturbance?

In a submarine equipped with sonar,the time between the transmission of ultrasonic signals and the reception of the echo after reflection is found to be $80 \, s$. Find the distance of the obstacle from the submarine,given that the speed of sound in water is $1530 \, m s^{-1}$. (in $, m$)

$(i)$ What does the acronym $SONAR$ stand for?
$(ii)$ What is the audible range of sound for human beings?
$(iii)$ How do the bats search and catch their prey in dark night?

What is a transverse wave?

Why do astronauts talk to each other through radio telephones?