An engine moving away from a vertical cliff blows a horn at a frequency $f$. Its speed is $0.5 \%$ of the speed of sound in air. The frequency of the reflected sound received at the engine is ............ $f$.

An observer moves towards a stationary source of sound with a speed $\frac{1}{5}^{\text{th}}$ of the speed of sound. The wavelength and frequency of the waves emitted by the source are $\lambda$ and $f$ respectively. The apparent frequency and wavelength heard by the observer are respectively,

When the source of sound and the observer both are moving towards each other,the observer will hear:

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).

Which of the following statements is false?

$A$ 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: