Name the waves of frequency greater than $20,000 \,Hz$. Give one use of these waves.

State whether the following statement is true or false:
Sound travels faster at a higher temperature than at a lower temperature.

$(i)$ Which property of sound wave determines:
$(a)$ loudness
$(b)$ pitch?
$(ii)$ $A$ $SONAR$ station picks up a return signal after $3 \ s$. How far away is the object? (Speed of sound in water is $1440 \ m \ s^{-1}$)
$(iii)$ How can reverberations in a big hall or auditorium be reduced?

What is a transverse wave?

If the density of a medium through which sound is propagating is minimum,then this point is called:

$A$ 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?