Two cars $A$ and $B$ are moving in the same direction with speeds $36 \, km/hr$ and $54 \, km/hr$ respectively. Car $B$ is ahead of $A$. If $A$ sounds a horn of frequency $1000 \, Hz$ and the speed of sound in air is $340 \, m/s$,the frequency of sound received by the driver of car $B$ is ..... $Hz$.

$A$ bus is moving with a velocity of $5 \,m/s$ towards a wall. The driver blows the horn of frequency $165 \,Hz$. If the speed of sound in air is $335 \,m/s$, then after reflection of sound wave, the number of beats per second heard by the passengers in the bus will be

$A$ car blowing a horn of frequency $350\, Hz$ is moving towards a wall with a speed of $5\, m/s$. The beat frequency heard by a person standing between the car and the wall is ..... $Hz$ (speed of sound in air $= 350\, m/s$).

$A$ train moving at a speed of $220\, m s^{-1}$ towards a stationary object,emits a sound of frequency $1000\, Hz$. Some of the sound reaching the object gets reflected back to the train as an echo. The frequency of the echo as detected by the driver of the train is ...... $Hz$. (Speed of sound in air is $330\, m s^{-1}$)

Consider the Doppler effect in two cases. In the first case,an observer moves towards a stationary source of sound with a speed of $50 \,m/s$. In the second case,the observer is at rest and the source moves towards the observer with the same speed of $50 \,m/s$. Then the frequency heard by the observer will be [velocity of sound in air $= 330 \,m/s$.]

$A$ reflector is moving with $20 \,m/s$ towards a stationary source of sound. If the source is producing sound waves of $160 \,Hz$, then the wavelength of the reflected wave is (speed of sound in air is $340 \,m/s$).