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,

Two sources of sound $S_1$ and $S_2$ are moving towards and away from a stationary observer with the same speed $V$ respectively. The observer detects $3$ beats per second. Find the speed of the source (approximately) in $m/s$. Given: $f_1 = f_2 = 500 \, Hz$,speed of sound in air $= 330 \, m/s$.

$A$ sound source $S$ is moving along a straight track with speed $v,$ and is emitting sound of frequency $v_{0}.$ An observer is standing at a finite distance,at the point $O,$ from the track. The time variation of frequency heard by the observer is best represented by (where $t_{0}$ represents the instant when the distance between the source and observer is minimum).

$A$ 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 $....... \, km/hr$.

$A$ bat moving at $10\,ms^{-1}$ towards a wall sends a sound signal of $8000\,Hz$ towards it. On reflection it hears a sound of frequency $f$. The value of $f$ in $Hz$ is close to (speed of sound $= 320\,ms^{-1}$)

Two men are walking along a horizontal straight line in the same direction. The man in front walks at a speed $1.0 \ m \ s^{-1}$ and the man behind walks at a speed $2.0 \ m \ s^{-1}$. $A$ third man is standing at a height $12 \ m$ above the same horizontal line such that all three men are in a vertical plane. The two walking men are blowing identical whistles which emit a sound of frequency $1430 \ Hz$. The speed of sound in air is $330 \ m \ s^{-1}$. At the instant when the moving men are $10 \ m$ apart,the stationary man is equidistant from them. The frequency of beats in $Hz$ heard by the stationary man at this instant is: