Question 2: A police car is travelling at 100 km h-1 South down a road, on a day when the air speed of sound in New York
Posted: Mon May 16, 2022 3:34 pm
Question 2:
A police car is travelling at 100 km h-1 South down a road, on a
day when the air speed of sound in New York is 1 230
km/h. The police hear their siren making a ‘bee-baa’
sound, where the ‘bee’ is 639 Hz and the
‘baa’ is 540 Hz. Because of the Doppler
effect:
1) A person standing on the side of the
road hears what hertz of bee and how many
hertz of baa?
2) As the police car comes towards them how many hertz of
bee and how many herts of baa do they
hear after the police car has passed them?
3) How many hertz of bee and how many hertz of baa do people
travelling towards the police car at 80 km/h North (relative to the
earth) hear?
(Hint: do a sanity check on your answers to check whether the
frequency increases/decreases as expected).
A police car is travelling at 100 km h-1 South down a road, on a
day when the air speed of sound in New York is 1 230
km/h. The police hear their siren making a ‘bee-baa’
sound, where the ‘bee’ is 639 Hz and the
‘baa’ is 540 Hz. Because of the Doppler
effect:
1) A person standing on the side of the
road hears what hertz of bee and how many
hertz of baa?
2) As the police car comes towards them how many hertz of
bee and how many herts of baa do they
hear after the police car has passed them?
3) How many hertz of bee and how many hertz of baa do people
travelling towards the police car at 80 km/h North (relative to the
earth) hear?
(Hint: do a sanity check on your answers to check whether the
frequency increases/decreases as expected).