Doppler Effect
WAVES

172976 A motor cycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration 2 $\mathrm{ms}^{-2}$. Distance travelled by the motor cycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency, is nearly (speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

1 $49 \mathrm{~m}$
2 $98 \mathrm{~m}$
3 $147 \mathrm{~m}$
4 $196 \mathrm{~m}$
WAVES

172977 A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed $u$ in a direction perpendicular to the wall measures a frequency $f^{\prime}=\frac{11}{8} f$ at the instant shown, then $u$ is related to the speed of sound $v_{s}$ as

1 $\frac{3}{4} \mathrm{v}_{\mathrm{s}}$
2 $\frac{3}{8} \mathrm{v}_{\mathrm{s}}$
3 $\frac{1}{4} \mathrm{v}_{\mathrm{s}}$
4 $\frac{8}{3} \mathrm{v}_{\mathrm{s}}$
WAVES

172998 A stationary police car sounds a siren with a frequency of $990 \mathrm{~Hz}$. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, an observer, driving towards the car with a speed of $33 \mathrm{~m} / \mathrm{s}$, will hear a frequency of

1 $891 \mathrm{~Hz}$
2 $900 \mathrm{~Hz}$
3 $1089 \mathrm{~Hz}$
4 $1100 \mathrm{~Hz}$
WAVES

172979 A rocket is moving at a speed of $200 \mathrm{~ms}^{-1}$ towards a stationary target. While moving it emits a wave of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the echo as detected by the rocket is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

1 $1000 \mathrm{~Hz}$
2 $1580 \mathrm{~Hz}$
3 $2540 \mathrm{~Hz}$
4 $4080 \mathrm{~Hz}$
WAVES

172981 A car is moving with $90 \mathrm{~km} / \mathrm{h}$ blows a horn of $150 \mathrm{~Hz}$, towards a cliff. The frequency of the reflected sound heard by the driver will be (speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )-

1 $150 \mathrm{~Hz}$
2 $140 \mathrm{~Hz}$
3 $180 \mathrm{~Hz}$
4 $174 \mathrm{~Hz}$
WAVES

172976 A motor cycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration 2 $\mathrm{ms}^{-2}$. Distance travelled by the motor cycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency, is nearly (speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

1 $49 \mathrm{~m}$
2 $98 \mathrm{~m}$
3 $147 \mathrm{~m}$
4 $196 \mathrm{~m}$
WAVES

172977 A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed $u$ in a direction perpendicular to the wall measures a frequency $f^{\prime}=\frac{11}{8} f$ at the instant shown, then $u$ is related to the speed of sound $v_{s}$ as

1 $\frac{3}{4} \mathrm{v}_{\mathrm{s}}$
2 $\frac{3}{8} \mathrm{v}_{\mathrm{s}}$
3 $\frac{1}{4} \mathrm{v}_{\mathrm{s}}$
4 $\frac{8}{3} \mathrm{v}_{\mathrm{s}}$
WAVES

172998 A stationary police car sounds a siren with a frequency of $990 \mathrm{~Hz}$. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, an observer, driving towards the car with a speed of $33 \mathrm{~m} / \mathrm{s}$, will hear a frequency of

1 $891 \mathrm{~Hz}$
2 $900 \mathrm{~Hz}$
3 $1089 \mathrm{~Hz}$
4 $1100 \mathrm{~Hz}$
WAVES

172979 A rocket is moving at a speed of $200 \mathrm{~ms}^{-1}$ towards a stationary target. While moving it emits a wave of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the echo as detected by the rocket is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

1 $1000 \mathrm{~Hz}$
2 $1580 \mathrm{~Hz}$
3 $2540 \mathrm{~Hz}$
4 $4080 \mathrm{~Hz}$
WAVES

172981 A car is moving with $90 \mathrm{~km} / \mathrm{h}$ blows a horn of $150 \mathrm{~Hz}$, towards a cliff. The frequency of the reflected sound heard by the driver will be (speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )-

1 $150 \mathrm{~Hz}$
2 $140 \mathrm{~Hz}$
3 $180 \mathrm{~Hz}$
4 $174 \mathrm{~Hz}$
NEET Test Series from KOTA - 10 Papers In MS WORD WhatsApp Here
WAVES

172976 A motor cycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration 2 $\mathrm{ms}^{-2}$. Distance travelled by the motor cycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency, is nearly (speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

1 $49 \mathrm{~m}$
2 $98 \mathrm{~m}$
3 $147 \mathrm{~m}$
4 $196 \mathrm{~m}$
WAVES

172977 A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed $u$ in a direction perpendicular to the wall measures a frequency $f^{\prime}=\frac{11}{8} f$ at the instant shown, then $u$ is related to the speed of sound $v_{s}$ as

1 $\frac{3}{4} \mathrm{v}_{\mathrm{s}}$
2 $\frac{3}{8} \mathrm{v}_{\mathrm{s}}$
3 $\frac{1}{4} \mathrm{v}_{\mathrm{s}}$
4 $\frac{8}{3} \mathrm{v}_{\mathrm{s}}$
WAVES

172998 A stationary police car sounds a siren with a frequency of $990 \mathrm{~Hz}$. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, an observer, driving towards the car with a speed of $33 \mathrm{~m} / \mathrm{s}$, will hear a frequency of

1 $891 \mathrm{~Hz}$
2 $900 \mathrm{~Hz}$
3 $1089 \mathrm{~Hz}$
4 $1100 \mathrm{~Hz}$
WAVES

172979 A rocket is moving at a speed of $200 \mathrm{~ms}^{-1}$ towards a stationary target. While moving it emits a wave of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the echo as detected by the rocket is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

1 $1000 \mathrm{~Hz}$
2 $1580 \mathrm{~Hz}$
3 $2540 \mathrm{~Hz}$
4 $4080 \mathrm{~Hz}$
WAVES

172981 A car is moving with $90 \mathrm{~km} / \mathrm{h}$ blows a horn of $150 \mathrm{~Hz}$, towards a cliff. The frequency of the reflected sound heard by the driver will be (speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )-

1 $150 \mathrm{~Hz}$
2 $140 \mathrm{~Hz}$
3 $180 \mathrm{~Hz}$
4 $174 \mathrm{~Hz}$
WAVES

172976 A motor cycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration 2 $\mathrm{ms}^{-2}$. Distance travelled by the motor cycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency, is nearly (speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

1 $49 \mathrm{~m}$
2 $98 \mathrm{~m}$
3 $147 \mathrm{~m}$
4 $196 \mathrm{~m}$
WAVES

172977 A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed $u$ in a direction perpendicular to the wall measures a frequency $f^{\prime}=\frac{11}{8} f$ at the instant shown, then $u$ is related to the speed of sound $v_{s}$ as

1 $\frac{3}{4} \mathrm{v}_{\mathrm{s}}$
2 $\frac{3}{8} \mathrm{v}_{\mathrm{s}}$
3 $\frac{1}{4} \mathrm{v}_{\mathrm{s}}$
4 $\frac{8}{3} \mathrm{v}_{\mathrm{s}}$
WAVES

172998 A stationary police car sounds a siren with a frequency of $990 \mathrm{~Hz}$. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, an observer, driving towards the car with a speed of $33 \mathrm{~m} / \mathrm{s}$, will hear a frequency of

1 $891 \mathrm{~Hz}$
2 $900 \mathrm{~Hz}$
3 $1089 \mathrm{~Hz}$
4 $1100 \mathrm{~Hz}$
WAVES

172979 A rocket is moving at a speed of $200 \mathrm{~ms}^{-1}$ towards a stationary target. While moving it emits a wave of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the echo as detected by the rocket is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

1 $1000 \mathrm{~Hz}$
2 $1580 \mathrm{~Hz}$
3 $2540 \mathrm{~Hz}$
4 $4080 \mathrm{~Hz}$
WAVES

172981 A car is moving with $90 \mathrm{~km} / \mathrm{h}$ blows a horn of $150 \mathrm{~Hz}$, towards a cliff. The frequency of the reflected sound heard by the driver will be (speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )-

1 $150 \mathrm{~Hz}$
2 $140 \mathrm{~Hz}$
3 $180 \mathrm{~Hz}$
4 $174 \mathrm{~Hz}$
WAVES

172976 A motor cycle starts from rest from a stationary source of sound and moves away from the source with a uniform acceleration 2 $\mathrm{ms}^{-2}$. Distance travelled by the motor cycle when the person on it hears the sound of frequency which is $94 \%$ of the true frequency, is nearly (speed of sound in air $=330 \mathrm{~ms}^{-1}$ )

1 $49 \mathrm{~m}$
2 $98 \mathrm{~m}$
3 $147 \mathrm{~m}$
4 $196 \mathrm{~m}$
WAVES

172977 A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed $u$ in a direction perpendicular to the wall measures a frequency $f^{\prime}=\frac{11}{8} f$ at the instant shown, then $u$ is related to the speed of sound $v_{s}$ as

1 $\frac{3}{4} \mathrm{v}_{\mathrm{s}}$
2 $\frac{3}{8} \mathrm{v}_{\mathrm{s}}$
3 $\frac{1}{4} \mathrm{v}_{\mathrm{s}}$
4 $\frac{8}{3} \mathrm{v}_{\mathrm{s}}$
WAVES

172998 A stationary police car sounds a siren with a frequency of $990 \mathrm{~Hz}$. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, an observer, driving towards the car with a speed of $33 \mathrm{~m} / \mathrm{s}$, will hear a frequency of

1 $891 \mathrm{~Hz}$
2 $900 \mathrm{~Hz}$
3 $1089 \mathrm{~Hz}$
4 $1100 \mathrm{~Hz}$
WAVES

172979 A rocket is moving at a speed of $200 \mathrm{~ms}^{-1}$ towards a stationary target. While moving it emits a wave of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the target gets reflected back to the rocket as an echo. The frequency of the echo as detected by the rocket is (velocity of sound $=330 \mathrm{~ms}^{-1}$ )

1 $1000 \mathrm{~Hz}$
2 $1580 \mathrm{~Hz}$
3 $2540 \mathrm{~Hz}$
4 $4080 \mathrm{~Hz}$
WAVES

172981 A car is moving with $90 \mathrm{~km} / \mathrm{h}$ blows a horn of $150 \mathrm{~Hz}$, towards a cliff. The frequency of the reflected sound heard by the driver will be (speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )-

1 $150 \mathrm{~Hz}$
2 $140 \mathrm{~Hz}$
3 $180 \mathrm{~Hz}$
4 $174 \mathrm{~Hz}$