$A$ sound source of frequency $170 \, Hz$ is placed near a wall. $A$ man walking from the source towards the wall finds that there is a periodic rise and fall of sound intensity. If the speed of sound in air is $340 \, m/s$,the distance (in metres) separating the two adjacent positions of minimum intensity is

$A$ string fixed at one end and free at the other is vibrating in its second overtone. The length of the string is $10 \ cm$ and the maximum amplitude of vibration of particles of the string is $2 \ mm$. Then the amplitude of the particle at $9 \ cm$ from the fixed end is

$A$ string is vibrating in its fifth overtone between two rigid supports $2.4 \ m$ apart. The distance between successive node and antinode is (in $m$)

Standing waves are produced in a $10 \; m$ long stretched string. If the string vibrates in $5$ segments and the wave velocity is $20 \; m/s$,the frequency is ... $Hz$.

$A$ suspension bridge is to be built across a valley where it is known that the wind can gust at $5 \,s$ intervals. It is estimated that the speed of transverse waves along the span of the bridge would be $400 \,m/s$. The danger of resonant motions in the bridge at its fundamental frequency would be greater if the span had a length of .......... $m$.

Match Column - $A$ with Column - $B$.

Column - $A$	Column - $B$
$(a)$ Minimum change in pressure	$(i)$ Antinodal point
$(b)$ Maximum change in pressure	$(ii)$ Nodal point