173031 A sounding source of frequency $500 \mathrm{~Hz}$ moves towards a stationary observer with a velocity $30 \mathrm{~m} / \mathrm{s}$. If the velocity of sound in air is $330 \mathrm{~m} / \mathrm{s}$, find the frequency hearted by the observer.

173032 Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of $72 \mathrm{~km} / \mathrm{h}$ and $36 \mathrm{~km} / \mathrm{h}$. If first car blows horn of frequency $280 \mathrm{~Hz}$, then the frequency of horn heard by the driver of second car when line joining the car makes angle of $45^{\circ}$ with the roads, will be

173033 A car is moving with a speed of $72 \mathrm{~km} \mathrm{~h}^{-1}$ towards a roadside source that emits sound at a frequency of $850 \mathrm{~Hz}$. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is $340 \mathrm{~ms}^{-1}$, the difference of the two frequencies, the driver hears is

173034 Two trains are moving towards each other with speeds of $20 \mathrm{~m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ relative to the ground. The first train sounds a whistle of frequency $600 \mathrm{~Hz}$, the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )

173031 A sounding source of frequency $500 \mathrm{~Hz}$ moves towards a stationary observer with a velocity $30 \mathrm{~m} / \mathrm{s}$. If the velocity of sound in air is $330 \mathrm{~m} / \mathrm{s}$, find the frequency hearted by the observer.

173032 Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of $72 \mathrm{~km} / \mathrm{h}$ and $36 \mathrm{~km} / \mathrm{h}$. If first car blows horn of frequency $280 \mathrm{~Hz}$, then the frequency of horn heard by the driver of second car when line joining the car makes angle of $45^{\circ}$ with the roads, will be

173033 A car is moving with a speed of $72 \mathrm{~km} \mathrm{~h}^{-1}$ towards a roadside source that emits sound at a frequency of $850 \mathrm{~Hz}$. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is $340 \mathrm{~ms}^{-1}$, the difference of the two frequencies, the driver hears is

173034 Two trains are moving towards each other with speeds of $20 \mathrm{~m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ relative to the ground. The first train sounds a whistle of frequency $600 \mathrm{~Hz}$, the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )

173031 A sounding source of frequency $500 \mathrm{~Hz}$ moves towards a stationary observer with a velocity $30 \mathrm{~m} / \mathrm{s}$. If the velocity of sound in air is $330 \mathrm{~m} / \mathrm{s}$, find the frequency hearted by the observer.

173032 Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of $72 \mathrm{~km} / \mathrm{h}$ and $36 \mathrm{~km} / \mathrm{h}$. If first car blows horn of frequency $280 \mathrm{~Hz}$, then the frequency of horn heard by the driver of second car when line joining the car makes angle of $45^{\circ}$ with the roads, will be

173033 A car is moving with a speed of $72 \mathrm{~km} \mathrm{~h}^{-1}$ towards a roadside source that emits sound at a frequency of $850 \mathrm{~Hz}$. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is $340 \mathrm{~ms}^{-1}$, the difference of the two frequencies, the driver hears is

173034 Two trains are moving towards each other with speeds of $20 \mathrm{~m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ relative to the ground. The first train sounds a whistle of frequency $600 \mathrm{~Hz}$, the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )

173031 A sounding source of frequency $500 \mathrm{~Hz}$ moves towards a stationary observer with a velocity $30 \mathrm{~m} / \mathrm{s}$. If the velocity of sound in air is $330 \mathrm{~m} / \mathrm{s}$, find the frequency hearted by the observer.

173032 Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of $72 \mathrm{~km} / \mathrm{h}$ and $36 \mathrm{~km} / \mathrm{h}$. If first car blows horn of frequency $280 \mathrm{~Hz}$, then the frequency of horn heard by the driver of second car when line joining the car makes angle of $45^{\circ}$ with the roads, will be

173033 A car is moving with a speed of $72 \mathrm{~km} \mathrm{~h}^{-1}$ towards a roadside source that emits sound at a frequency of $850 \mathrm{~Hz}$. The car driver listens to the sound while approaching the source and again while moving away from the source after crossing it. If the velocity of sound is $340 \mathrm{~ms}^{-1}$, the difference of the two frequencies, the driver hears is

173034 Two trains are moving towards each other with speeds of $20 \mathrm{~m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ relative to the ground. The first train sounds a whistle of frequency $600 \mathrm{~Hz}$, the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is $340 \mathrm{~m} / \mathrm{s}$ )