173078 A source producing sound of frequency $170 \mathrm{~Hz}$ is approaching a stationary observed with a velocity of $17 \mathrm{~ms}^{-1}$. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air $=\mathbf{3 4 0} \mathrm{ms}^{-1}$ )

173079 An observer is standing $500 \mathrm{~m}$ away from a vertical hill. Starting between the observer and the hill, a police van sounding a siren of frequency $1000 \mathrm{~Hz}$ moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is $970 \mathrm{~Hz}$, the frequency of the sound heard after reflection from the hill (in $\mathrm{Hz}$ ) is about, (velocity of sound $=300 \mathrm{~ms}^{-1}$ )

173080 A vehicle sounding a whistle of frequency 256 $\mathrm{Hz}$ is moving on a straight road, towards a hill with a velocity of $10 \mathrm{~ms}^{-1}$. The number of beats per second observed by a person travelling in the vehicle is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

173081 A sound wave has frequency of $2 \mathrm{kHz}$ and wavelength of $35 \mathrm{~cm}$. If an observer is $1.4 \mathrm{~km}$ away from the source, after what time interval could the observer hear the sound?

173078 A source producing sound of frequency $170 \mathrm{~Hz}$ is approaching a stationary observed with a velocity of $17 \mathrm{~ms}^{-1}$. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air $=\mathbf{3 4 0} \mathrm{ms}^{-1}$ )

173079 An observer is standing $500 \mathrm{~m}$ away from a vertical hill. Starting between the observer and the hill, a police van sounding a siren of frequency $1000 \mathrm{~Hz}$ moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is $970 \mathrm{~Hz}$, the frequency of the sound heard after reflection from the hill (in $\mathrm{Hz}$ ) is about, (velocity of sound $=300 \mathrm{~ms}^{-1}$ )

173080 A vehicle sounding a whistle of frequency 256 $\mathrm{Hz}$ is moving on a straight road, towards a hill with a velocity of $10 \mathrm{~ms}^{-1}$. The number of beats per second observed by a person travelling in the vehicle is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

173081 A sound wave has frequency of $2 \mathrm{kHz}$ and wavelength of $35 \mathrm{~cm}$. If an observer is $1.4 \mathrm{~km}$ away from the source, after what time interval could the observer hear the sound?

173078 A source producing sound of frequency $170 \mathrm{~Hz}$ is approaching a stationary observed with a velocity of $17 \mathrm{~ms}^{-1}$. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air $=\mathbf{3 4 0} \mathrm{ms}^{-1}$ )

173079 An observer is standing $500 \mathrm{~m}$ away from a vertical hill. Starting between the observer and the hill, a police van sounding a siren of frequency $1000 \mathrm{~Hz}$ moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is $970 \mathrm{~Hz}$, the frequency of the sound heard after reflection from the hill (in $\mathrm{Hz}$ ) is about, (velocity of sound $=300 \mathrm{~ms}^{-1}$ )

173080 A vehicle sounding a whistle of frequency 256 $\mathrm{Hz}$ is moving on a straight road, towards a hill with a velocity of $10 \mathrm{~ms}^{-1}$. The number of beats per second observed by a person travelling in the vehicle is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

173081 A sound wave has frequency of $2 \mathrm{kHz}$ and wavelength of $35 \mathrm{~cm}$. If an observer is $1.4 \mathrm{~km}$ away from the source, after what time interval could the observer hear the sound?

173078 A source producing sound of frequency $170 \mathrm{~Hz}$ is approaching a stationary observed with a velocity of $17 \mathrm{~ms}^{-1}$. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air $=\mathbf{3 4 0} \mathrm{ms}^{-1}$ )

173079 An observer is standing $500 \mathrm{~m}$ away from a vertical hill. Starting between the observer and the hill, a police van sounding a siren of frequency $1000 \mathrm{~Hz}$ moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is $970 \mathrm{~Hz}$, the frequency of the sound heard after reflection from the hill (in $\mathrm{Hz}$ ) is about, (velocity of sound $=300 \mathrm{~ms}^{-1}$ )

173080 A vehicle sounding a whistle of frequency 256 $\mathrm{Hz}$ is moving on a straight road, towards a hill with a velocity of $10 \mathrm{~ms}^{-1}$. The number of beats per second observed by a person travelling in the vehicle is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

173081 A sound wave has frequency of $2 \mathrm{kHz}$ and wavelength of $35 \mathrm{~cm}$. If an observer is $1.4 \mathrm{~km}$ away from the source, after what time interval could the observer hear the sound?