Doppler shift Definition and 148 Threads

Just some conceptual ideas that I don't understand A spaceship starts falling under gravity with an acceleration g as measured by an observer Barry at rest on Earth. At the instant that the ship starts to fall, an astronaut Harry at the base of the rocket ship sends a light signal of frequency...

1. Homework Statement You are standing on side of road and ambulance drives by. Smallest distance between you and ambulance is 4m. Ambulance v=10m/s^2. You have 2.2 GHz radar. Ambulance travels 100m with center of straight line directly across from you. Compute exact doppler shift by taking...

Homework Statement The Sun rotates with a period of 24.7 days and has a radius of 7.00 x 108 m. For a terrestrial observer, Calculate the resultant Doppler shift of light of wavelength 500 nm which is emitted from the solar equator at : i)each side of the disc, ii)the center of the solar disc...

I have come to learn that the Doppler shift equation is asymmetric. That is, the Doppler shift is not the same when source is moving towards the observer or when the observer is moving towards the observer (both with same speed). I have looked at the derivation of the Doppler shift equation...

Homework Statement Space probes communicate with controllers on Earth using radio waves. Suppose a probe has a radio-transmitter that operates at a frequency of 516.0 MHz when at rest relative to the observer. This probe is now wandering the solar system. The signal you pick up from the probe...

I understand mathematically etc how light can doppler shift when looked at as a wave but can it be understood how light doppler shifts as a photon i.e. could just one photon be doppler shifted? For example; Say there is an atom with energy levels 1 and 2. One observer, stationary relative to...

I've just begun to study spectroscopy, and I need a clarification about the Doppler Effect. Consider a cell containing Rubidium and enlight it with a laser. Connect the system with an oscilloscope and give a triangular wave as input (so you can know when the Rubidium is resonant). This is the...

How do Doppler shifts work for light if, according to special relativity, light is constant velocity for all observers? So if c is unchanged, then surely wavelength and frequency don't change. I appreciate that I must be misunderstanding something, because redshift on stars occurs, but I am...

Hello, the internet. I am attempting to graph Doppler Shift as a function of time for a music project. The equation for observed frequency is: fo=fs(c)/vs(c) Where fo is observed frequency fs is the source frequency c is the speed of sound vs is the velocity of the source But...

Hi, I was looking up the formula for this on wikipedia and it said that the frequency shift is: \frac{\sqrt{1 - v^2/c^2}}{1+\frac{v}{c}\cos{\theta}} In the case where the the emitter is directly above the observer when the photon arrives it says it simplifies to: \gamma =...

I've got a somewhat simple question, and I think its from me overlooking something stupid...but how does using doppler shift work if in any moving rest frame the speed of light is supposed to stay at 3(10^8) m/s? I know that E=hc/λ, so for the wavelength of the light λ to change, the only thing...

Homework Statement What's the doppler shift (Δf) of the object moving away from us if we measure a wavelength of light λ=1.55μm emitted from it and it's at a distance of 10 megaparsecs? And is the object red or blue shifted? Added information to the problem is for each megaparsec the object...

Hello all, so let's suppose a photon is being gravitationally red or blue shifted changing its frequency which ultimately changes its energy, where does this energy change come from?

Homework Statement Mary is blowing her trombone at 400hz. Paul is approaching her at speed v, blowing the same type of trombone. These trombones has a maximum frequency of 500hz. What is the maximum speed Paul can approach Mary, and still cancel out her trombone noise? Homework...

I was just wondering if this problem is right and I'm missing something or ... http://www.astronomy.ohio-state.edu/~ryden/ast143/ps3_soln.pdf Cuz I'm reading the GRE book and it says here to use the relativistic Doppler shift formula. So the problem in the link would need to be solved like...

Doppler Shift/ Doppler effect! HELP 1. A police car is traveling at a constant speed of 110. km/h with a radar gun which generates and detects radiowaves. The police car and the ambulance drive directly towards each other. The radar gun produces radiowaves with a wavelength of 0.0440 m. An...

Hi all, It is my understanding that a Doppler shift is the result of a change in wave frequency due to a change in distance of a signal source, relative to the observer. I assume that the change in distance must be continuous, in order to observe a Doppler effect: frequency increase =...

Hi all, Let's say you are at rest with respect to the galaxy, and you have low energy photons all around you. Now, if I crank my energies up relatvisitcally, the frequency and thus E = hf of those photons will increase. Red Light becomes Blue Light, Blue Light becomes UV, UV to X-ray, and...

Homework Statement light signal of frequency 33 MHz is reflected off a (radio)mirror that is moving toward you at half the speed of light. What is the reflected frequency in Hz?Homework Equations f_f = f*sqrt((1-v/c)/(1+v/c)The Attempt at a Solution The mirror and light wave are approaching...

Hi, I'm trying to adapt the doppler shift formula for a stationary listener and a source traveling in a straight line towards/away from the listener to the case where the source does not move straight towards the listener. For example, suppose that I am looking north and train further in the...

http://en.wikipedia.org/wiki/List_of_relativistic_equations#Doppler_shift and http://www.physics.umanitoba.ca/~souther/waves02/feb0402/sld011.htm If you look at the derivation on Wikipedia: v' = γv But the one on Uni of Manitoba shows: f' = f0(1-β^2)^(1/2) or f' = f/γ...

As the title says, I'm interested in the precision a Doppler shift can be revealed. That's why I read that it's possible to detect exo-planets by measuring the Doppler shift of the star's spectra. Works like this: the stars moves, since it moves back and forth is spectrum suffer from Doppler...

Homework Statement i am using the Doppler shift formula Fs=F0(1/1+-(vsource/c) i can rearrange it to an extent but when i use it to find my answer i i need to divide it by two in order to do it, every time. I would just like to understand why this is, or if i am doing it completely wrong...

Homework Statement You are standing on the side of the Trans-Canada Highway as the Physicsmobile approaches you. As it approaches, you hear an engine noise of 1100 Hz. After it passes, you hear an engine noise of 950 Hz. How fast was the Physicsmobile travelling? Homework Equations...

... In other words a photon is energy-mass equivalent so it is effected by gravity. If the photon comes from a place of very high gravity, and we see it shifted, does the emitter have to be moving? ( this is a trick question. I'm heading to Mach's Principle :-) If high gravity can dopple...

A police car is traveling at a constant speed of 100. km/h with a radar gun which generates and detects radiowaves. The police car and the ambulance drive directly towards each other. The radar gun produces radiowaves with a wavelength of 0.0650 m. What doppler shift (Δf = f′–f) is detected...

I recently heard about the effects from The Doppler Effects at high relative speeds (significant fractions of c). For example you will eventually will even get burned/die by the radiation of the CMBR being ao intensly blueshifted while you're approaching the speed of light (relative). So...

Given the Doppler shift equation quoted here: http://en.wikipedia.org/wiki/Doppler_effect#General \frac{f_r}{f_s} = \left(\frac{c + v_r}{c + v_s} \right) where c is the velocity of waves in the medium; vr is the velocity of the receiver relative to the medium; positive if the receiver is...

I was considering the following question; 'A fire engine traveling at 70m/s drives past a van traveling at 30m/s. The speed of sound in air is 330m/s and the fire engine has a frequency of 200Hz when stationary. At what frequency does the van driver hear the siren?' I understand you have...

If this is the wrong place to be posting this, feel free to lock this thread. I wasn't sure if this belonged in "classical physics" or "quantum physics"; this seemed like the appropriate place, but I'm not 100% certain, as it does involve subatomic particles. Anyways, to get to the matter at...

Homework Statement a) Calculate the Doppler shift due to a relative velocity of 3cm/sec. b) Fine \Delta E/E, where E = 14.4keV and \Delta E is the Doppler shift obtained in (a). Homework Equations \frac{f_{0}}{f_{s}}=\frac{c}{c+v_{s}} The Attempt at a Solution So I'm working on...

I have re-written this as as I accidently deleted my original post. I was wondering if the relativistic Doppler shift of a reflection from a mirror moving away from the observer was the same as the Newtonian equation in the special case that the mirror is orthogonal to the direction of motion...

Homework Statement P15. The police car with its 300 Hz siren is moving toward a warehouse at 30 m/s, intending to crash through the door. What frequency does the driver of the police car hear reflected from the warehouse? (5 marks) Homework Equations doppler shift for an approaching...

Homework Statement How fast would a star have to travel to make violet light (λ = 400 nm) appear to be blue (λ = 450 nm)? Assume the star is moving along the line that connects the star to the Earth. Homework Equations λr = λc / (c-Vr) f= fo (c +- Vr / c +- Vs) The Attempt at a...

Homework Statement Estimate the Doppler shift for a radio wave reflected from an airplane moving directly toward you at a speed of 292 m/s. Assume the radio wave has a frequency of 9.7x10^6 Hz. Homework Equations fo = fv/(v − vt) The Attempt at a Solution Using the above...

Hi, I'm trying to understand a derivation / question for my revision. It has to do with the four momentum of a photon and doppler/redshifts. Homework Statement Show that ratio between emitted and received frequencies (for two observers E and R moving with velocities u and v respectively)...

Hi! I have two (stupid) questions: 1) We can determine what elements are present in distant stars by studying their spectrum, right? But if the spectrum of some star is redshifted, wouldn't we be fooled into believing some elements to be present there that might not really be there, due to...

Homework Statement A bat is pursuing an insect, and using echolocation of 41 kHz sound waves to track the insect. The insect is initially 34 cm from the bat but then moves to a distance of 44 cm as it tries to escape. What is the difference in the two echo times that the bat measures...

Homework Statement Light with a frequency of 6.1(1014) Hz is measured from a star known to produce light with a frequency of 6.0(1014). How fast is the star moving toward or away from earth? Homework Equations f = f0(v + vo)/(v-vs. f=observed frequency f0 = original frequency v=wave speed vo =...

My physics teacher has informed us that for our mock waves exam we are going to be given some relativistic questions on doppler shift, as an experiment by our loving masters. We derived the Lorentz factor and some shift equations, but we haven't done anything else and I'd really like some...

Hi, I've got a multiple choice piece of work to do with some questions I cannot figure out. They are: In regards to red shift, which one is Doppler shift defined as: 1. The increase in wavelength due to Doppler shift, of spectral lines from SPONTANEOUS photon emission from elements on cosmic...

So I'm planning to start a project using the Doppler shift to calculate the velocity of a moving object. The problem is, I'm not sure which equations I should use, and I saw many different equations around the Internet. So are these equations correct? If not, can someone tell me what the...

I was talking to one of my friends the other day about doppler effect and we went into the discussion of accelerating object and doppler effect. we both agreed that the frequency shift would vary in time. then we argued about the frequency shift for different observers and here is were it got...

In "Does the inertia of a body depend upon its energy content?," http://fourmilab.ch/etexts/einstein/E_mc2/www/ , Einstein invokes a result from his 1905 SR paper, which is that the Doppler shift of a light wave's frequency D(v)=\sqrt{(1-v)/(1+v)} is also the factor by which its energy changes...

Homework Statement A man riding his bicycle was caught driving through a red traffic light. The man was taken to court and trialled where he claimed he was cycling so quickly that the light had appeared to be green to him due to the Doppler effect. The prosecution accepted his excuse but...

Homework Statement The Doppler shift was first tested in 1845 by the French scientist B. Ballot. He had a trumpet player sound a 463 Hz note while riding on a flat-car pulled by a locomotive. At the same time, a stationary trumpeter played the same note. Ballot heard 5 beats/s. How fast was...

Hi, I'm reading "The First Three Minutes" by Steven Weinberg And am confused about this paragraph... "Astronomers are able to measure the motion of a luminous body in a direction directly along the line of sight much more accurately than they can measure its motion at right angles to...

When we analyze the light coming from a distant galaxy, we find a particular absorption line with a wavelength of 1118 nm. This same absorption line in light from the sun has a wavelength of 625 nm is this galaxy moving towards us or away from us? Calculate the magnitude of the velocity of...

Homework Statement In a distant galaxy, an emission line of hydrogen that has a rest wavelength of 656 nm has an observed wavelength of 662.6 nm. Is the galaxy moving away from us or toward us? How fast is it moving in (km/sec)? Homework Equations velocity = ((shifted wavelength -...

Imagine this scenario: An aeroplane emits a sound wave. The sound wave propagates in all directions. a) If the plane is flying forward, it emits a sound towards a reflector in front of it. When the sound is reflected, its frequency is reduced, presuming the plane is traveling towards the...