$A$ train moves towards a stationary observer with speed $34\, m/s$. The train sounds a whistle and its frequency registered by the observer is $f_1$. If the speed of the train is reduced to $17\, m/s$,the frequency registered is $f_2$. If the speed of sound is $340\, m/s$,then the ratio $f_1/f_2$ is

$A$ motorcycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration $2 \,m/s^2$. The distance travelled by the motorcycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency is nearly (speed of sound in air $= 330 \,m/s$): (in $\,m$)

$A$ 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:

$A$ source $(S)$ of sound has a frequency of $240 \ Hz$. When the observer $(O)$ and the source move towards each other at a speed $v$ with respect to the ground (as shown in Case $1$ in the figure),the observer measures the frequency of the sound to be $288 \ Hz$. However,when the observer and the source move away from each other at the same speed $v$ with respect to the ground (as shown in Case $2$ in the figure),the observer measures the frequency of the sound to be $n \ Hz$. The value of $n$ is:

The frequency changes by $10 \%$ as a sound source approaches a stationary observer with constant speed $V_s$. What would be the percentage change in the frequency as the source recedes from the observer with the same speed $\left(V_s < V\right)$ (in $.5$)?

Two factories are sounding their sirens at $800 \, Hz$. $A$ man walks from one factory to the other at a speed of $2 \, m/s$. The velocity of sound is $320 \, m/s$. The number of beats heard by the person in one second will be: