Name the two types of mechanical waves.

State three factors on which the speed of sound in a medium depends.

$(a)$ What are the basic factors on which the speed of sound in a medium depends?
$(b)$ Why are sound waves called mechanical waves?
$(c)$ How will you differentiate a high-pitch sound from a low-pitch sound with the help of a graph?

$A$ stretched wire $0.5\, m$ long is made to vibrate in two different modes as shown in diagrams $(A)$ and $(B)$ given below:
$(i)$ If the wavelength of the wave produced in mode $(A)$ is $1\, m$,what is the wavelength of the wave produced in mode $(B)$ of the following diagram?
$(ii)$ In which case is the note produced louder? Give a reason for your answer.
$(iii)$ In which case is the pitch of the note produced higher? Give a reason for your answer.

Given that sound travels in air at $340 \, m s^{-1}$,find the wavelength of the waves in air produced by a $20 \, Hz$ sound source. If the same source is put in a water tank,what would be the wavelength of the sound waves in water? (Given,speed of the sound in water $= 1480 \, m s^{-1}$)

$A$ sound wave with frequency higher than $20 \,kHz$ is not audible for human ear. Answer the following in respect of this statement:
$(i)$ What is the term used for such a sound?
$(ii)$ Name two organisms producing sound in this range.
$(iii)$ Write an application of such a wave.