Question

The frequency will sound different if we hear a sound source
moving relative to us. This phenomenon is called the Doppler Effect
in Physics. An ambulance sounds a siren at 1515 Hz and passes a
cyclist moving at 2.12 m / s. After the ambulance passed, the
cyclist heard a siren sound at a frequency of 1501 Hz. The speed of
sound in the air is about 343 m / s.

What is the speed (speed) of the ambulance in (m / s)?

Answer #1

Let us say that the speed of the ambulance is v. It is given that the speed of the cyclist is 2.12 m/s. Since the ambulances passes by the cyclist we can assume that the speed of the ambulance is greater than the cyclist. Hence the heard frequency equation will be,

Here vs is the speed of source, in our case it will be relative speed between the cyclist and the ambulance which is,

Substituting the heard and source frequencies into the equation we can calculate the speed of ambulance as,

Hence the speed of the ambulance is **5.32
m/s.**

Standing at a crosswalk, you hear a frequency of 590 Hz from the
siren of an approaching ambulance. After the ambulance passes, the
observed frequency of the siren is 497 Hz. Determine the
ambulance's speed from these observations. (Take the speed of sound
to be 343 m/s.)

The siren on an ambulance is emitting a sound whose frequency is
2550 Hz. The speed of sound is 343 m/s. (a) If the ambulance is
stationary and you (the "observer") are sitting in a parked car,
what are the wavelength and the frequency of the sound you hear?
(b) Suppose that the ambulance is moving toward you at a speed of
26.2 m/s. Determine the wavelength and the frequency of the sound
you hear. (c) If the ambulance is...

A car moves at 20 m/s north. An ambulance passes it going 25 m/s
north, with its siren on, f = 500 Hz. Find the frequency heard in
the car when the ambulance is moving away. (The speed of sound in
air is 343 m/s)

A truck moving at 36 m/s passes a police car moving at 45 m/s in
the opposite direction. The frequency of the sound emitted by the
siren on the police car is 500 Hz and the speed of sound in air is
343 m/s.
(a) What is the frequency heard by an observer in the truck as
the police car approaches the truck?
(b) What is the frequency heard by an observer in the truck
after the police car passes...

An ambulance has a siren of frequency 880 Hz. You are sitting at
a stop light as the ambulance passes you, traveling at a constant
22 m/s. If the speed of sound is 343 m/s, what is the change in the
frequency that you hear as the ambulance passes you?
A.) -56 Hz B.) -53 Hz
C.) -60 Hz D.) -116
Hz E.) -113 Hz

A pedestrian standing on the sidewalk heard a frequency of 845
Hz when an ambulance is traveling away from him with a speed of
45.0 m/s. Speed of sound in air = 343 m/s
A) what is the frequency of the ambulance siren? Express your
answer using three significant figures.
B) Then the ambulance stopped for a few seconds while sounding
the siren. A driver in a car that is coming towards the ambulance
heard a frequency of 995 Hz....

An ambulance with a 200-Hz siren is moving at 30.0 m/s. Take the
speed of sound to be 340 m/s. a) What frequencies are observed by a
stationary person standing on the sidewalk as the ambulance
approaches and after it passes? b) Is this Doppler shift real or
just a sensory illusion?

A pedestrian standing on the sidewalk heard a frequency of 850
Hz when an ambulance is travelling away from him with a speed of
45.0 m/s m / s . Speed of the sound in air = 343 m/s Part A What is
the frequency of the ambulance's siren? Express your answer using
three significant figures. Part B Then the ambulance stopped for a
few seconds while sounding the siren. A driver in a car that is
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You are standing on the sidewalk and hear an ambulance siren at
500 Hz when the ambulance is approaching and at 400 Hz when the
ambulance is going away from you. How fast is the ambulance moving?
(Note: the speed of sound is 343 m/s).
a.) 38.1 m/s
b.)343 m/s
c.)58.6 m/s
d.)49.3 m/s
e.)12.2 m/s

(a)
What frequency (in Hz) is received by a person watching an
oncoming ambulance moving at 106 km/h and emitting a steady 850 Hz
sound from its siren? The speed of sound on this day is 345
m/s.
Hz
(b)
What frequency (in Hz) does she receive after the ambulance has
passed?
Hz

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