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 ..... $Hz$.

$A$ source of sound emits waves with frequency $f \, Hz$ and speed $V \, m/s$. Two observers move away from this source in opposite directions,each with a speed $0.2V$ relative to the source. The ratio of frequencies heard by the two observers will be

An observer moves towards a stationary source of sound of frequency $n$. The apparent frequency heard by him is $2n$. If the velocity of sound in air is $332 \, m/s$,then the velocity of the observer is .... $m/s$.

$A$ car sounding a horn of frequency $1000 \text{ Hz}$ passes an observer. The ratio of frequencies noted by the observer before and after the car passes is $11:9$. If the speed of sound is $V$,what is the speed of the car?

Two trucks heading in opposite directions, each with a speed of $0.1 u$, approach each other. The speed of sound is $u$. The driver of the first truck sounds his horn with a frequency of $495 \,Hz$. Let $v_1$ and $v_2$ be the frequencies heard by the driver of the second truck when the trucks are approaching each other and when the trucks have passed each other, respectively. The magnitude of $v_1 - v_2$ is (in $\,Hz$)

$A$ 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: