$A$ source and a listener are both moving towards each other with a speed of $\frac{V}{10}$ (where $V$ is the speed of sound). If the frequency of the sound note emitted by the source is $n$,then the frequency heard by the listener would be nearly:

An audio transmitter $(T)$ and a receiver $(R)$ are hung vertically from two identical massless strings of length $8 \ m$ with their pivots well separated along the $X$ axis. They are pulled from the equilibrium position in opposite directions along the $X$ axis by a small angular amplitude $\theta_0 = \cos^{-1}(0.9)$ and released simultaneously. If the natural frequency of the transmitter is $660 \ Hz$ and the speed of sound in air is $330 \ m/s$,the maximum variation in the frequency (in $Hz$) as measured by the receiver (Take the acceleration due to gravity $g = 10 \ m/s^2$) is:

Two trains are moving towards each other at speeds of $20 \, m/s$ and $15 \, m/s$ relative to the ground. The first train sounds a whistle of frequency $600 \, Hz$. The frequency of the whistle heard by a passenger in the second train before the trains meet is ...... $Hz$ (the speed of sound in air is $340 \, m/s$).

$A$ driver in a car,approaching a vertical wall,notices that the frequency of his car horn has changed from $440 \, Hz$ to $480 \, Hz$ when it gets reflected from the wall. If the speed of sound in air is $345 \, m/s,$ then the speed of the car is $....... \, km/hr$.

When a car is approaching the observer,the frequency of the horn is $100 \, Hz$. After passing the observer,it is $50 \, Hz$. If the observer moves with the car,the frequency will be $\frac{x}{3} \, Hz$ where $x = .....$

$A$ 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: