$A$ boy standing on a platform observes the frequency of a train horn as it passes by. The change in the frequency noticed as the train approaches and recedes him with a velocity of $108 \text{ km/h}$ is (speed of sound in air $= 330 \text{ m/s}$) (in $\%$)

$A$ bus is moving with a velocity of $5 \ m/s$ towards a huge wall. The driver sounds a horn of frequency $165 \ Hz$. If the speed of sound in air is $355 \ m/s$,the number of beats heard per second by a passenger on the bus will be:

$A$ car $A$ is chasing another car $B$ with a speed of $20 \, m/s$,sounding a horn of frequency $180 \, Hz$. Both cars are moving towards a stationary siren of frequency $170 \, Hz$. What is the speed of car $B$ so that it does not hear any beats (in $, m/s$)? (Speed of sound $= 340 \, m/s$)

$A$ source emitting sound of frequency $288 \,Hz$ is tied to a string of $100 \,cm$ length and rotated with an angular velocity of $20 \,rad/s$ in the horizontal plane. The range of frequencies heard by an observer standing at a distance of $5 \,m$ from the source is (in $Hz$) (Speed of sound in air $= 340 \,m/s$)

$A$ source and a listener are both moving towards each other with a speed of $v/10$,where $v$ is the speed of sound. If the frequency of the note emitted by the source is $f$,the frequency heard by the listener would be nearly:

$A$ train sounding a whistle of frequency $510 \,Hz$ approaches a station at $72 \,km/hr$. The frequency of the note heard by an observer on the platform as the train $(1)$ approaches the station and then $(2)$ recedes from the station are respectively (in hertz) (velocity of sound in air $= 320 \,m/s$).