$A$ 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 $= 320\,ms^{-1}$)

$A$ vehicle sounding a whistle of frequency $256 \,Hz$ is moving on a straight road towards a hill with a velocity of $10 \,ms^{-1}$. The number of beats per second observed by a person travelling in the vehicle is (velocity of sound $= 330 \,ms^{-1}$).

$A$ man sitting in a moving train hears the whistle of the engine. The frequency of the whistle is $600 \ Hz$.

$A$ source of sound $S$ is moving with a velocity of $50\,m/s$ towards a stationary observer. The observer measures the frequency of the sound as $1000\,Hz$. What will be the apparent frequency of the source when it is moving away from the observer after crossing him (in $,Hz$)? (Take the velocity of sound in air as $350\,m/s$)

$A$ 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 $340 \,m/s$).

$A$ whistle of frequency $500 \, Hz$ tied to the end of a string of length $1.2 \, m$ revolves at $400 \, rev/min$. $A$ listener standing some distance away in the plane of rotation of the whistle hears frequencies in the range (speed of sound $= 340 \, m/s$):