Doppler shift in frequency does not depend upon:

$A$ car sounding a horn of frequency $1200 \text{ Hz}$ passes a stationary observer. The ratio of frequencies of the horn noted by the observer before and after passing the car is $7:5$. If the speed of sound is $V$,the speed of the car is:

$A$ sound source is moving on a circular path of radius $R$ with constant angular speed $\omega$ in an anticlockwise direction and emits a frequency $n$. An observer performs simple harmonic motion along the path $QPR$ with time period $T = \frac{2\pi}{\omega}$ as shown in the figure. If at $t = 0$ the source is at $A$ and the observer is at $Q$,and assuming $OP$ is very large compared to the radius $R$ and $QP$,then:

When a source of sound crosses a stationary observer,the change in apparent frequency of sound observed by the observer,when $V_s << V$,will be -

$A$ rocket is moving at a speed of $200\; m s^{-1}$ towards a stationary target. While moving, it emits a wave of frequency $1000\; Hz$. Some of the sound reaching the target gets reflected back to the rocket as an echo. Calculate:
$(1)$ the frequency of the sound as detected by the target and
$(2)$ the frequency of the echo as detected by the rocket.

If a source emitting waves of frequency $F$ moves towards an observer with a velocity $V/3$ and the observer moves away from the source with a velocity $V/4$,the apparent frequency as heard by the observer will be ($V=$ velocity of sound).