If the frequency of a tuning fork is $400 \, Hz$ and the speed of sound in air is $340 \, m s^{-1}$,find how far sound travels when the tuning fork makes $16$ vibrations. (in $, m$)

The walls of a hall built for musical concert should

Explain with the help of a diagram,how defects in a metal block can be detected using ultrasound.

$A$ 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.

Which of the following are transferred from one place to another place by the waves?

The pulse rate of a man is $80$ beats in one minute. Calculate its frequency. (in $ Hz$)