Doppler Definition and 713 Threads

Homework Statement The frequency ratio of a semitone interval on the equally tempered scale is 2 1/12. A) Show that the ratio is 1.059 B) Find the speed of an automobile passing a listener in still air if the pitch of the car's horn drops a semitone between the times when the car is...

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...

Hello everyone, I'm trying to calculate the doppler shift in frequency of a moving source. I'm approaching the problem from two different frames of reference and getting inconsistent results. what am I missing here? consider the special case of transverse doppler effect (θ=π/2). light...

As you know,the formula for doppler effect is: f^{'}=\frac{v-v_{o}}{v-v_{s}}f relativity suggests(at least I think) that f^{'} for v_{o}=u and v_{s}=0 should be the same with f^{'} for v_{o}=0 and v_{s}=-u,otherwise,there will be a way for the listener to know that which one,sound...

I noticed that once I was talking to a friend close to me and then a vehicle passed by with a huge sound and then I merely heard what he said. Can someone explain me why ? even though that friend was close to me ? Does it have any connection with the Doppler effect ?

Homework Statement Superman is carrying a red lantern with wavelength 650nm. He flies toward you at a speed of 2.7x108 m/s. What is the observed wavelength?Homework Equations f'=\frac{f}{\left(1-\frac{v_s}{v}\right)} and f=\frac{c}{\lambda}The Attempt at a Solution I used the equation...

Homework Statement Superman has a blue light of wavelength 480nm. How fast must he fly away from you so that his light appears orange, with a wavelength of 600nm?Homework Equations f'=\frac{f}{\left(1+\frac{v_s}{v}\right)} and f=\frac{c}{\lambda}The Attempt at a Solution I used the equation...

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 =...

in the equation at: http://en.wikipedia.org/wiki/Radar#Doppler_effect what does the v stand for? it is not explained, only vobs and vs are explained. Thanks.

Homework Statement A stationary destroyer is equipped with sonar that sends out pulses of sound at 49.0 MHz. Reflected pulses are received from a submarine directly below with a time delay of 60.0 ms at a frequency of 48.966 MHz. If the speed of sound in seawater is 1.58 km/s, what is the...

In several papers, diagrams, etc. about atomic experiments I saw pairs of lasers beaming in opposite directions. Naive question: why two lasers are used instead of one and a mirror? Or even further: why six lasers are used (2 in each axis) instead of just one and bunch of mirrors?

Homework Statement A physics student drops a vibrating 421 Hz tuning fork down the elevator shaft of a tall building. The temperature in the shaft is 20 °C. When the student hears a frequency of 392 Hz, how far has the tuning fork fallen? fS = 421 Hz fL = 392 Hz VSOUND = 343 m/s...

Homework Statement A car stops at 50m to a road-railway junction. A train is moving with a constant velocity 35m/s towards the junction. If the train emits a siren at a frequency of 100Hz, calculate the maximum and the minimum frequency that can be heard by the car driver. velocity of...

Homework Statement Revered members, I have attached the image of Doppler effect explanation. Homework Equations I have the following doubts 1)t1 = L/v 2) t2 = T0 +( L + vsT0)/v But why T0 comes here, instead of ( L + vsT0)/v The Attempt at a Solution

Hi, I am doing doppler effect and this question wants me to prove that the wavelength perceived by the observer and that of the wave emitted is the same. I tried doing it but couldn't, so I checked out what they had as an answer: They said that the wavelength of the emitted wave is: v...

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...

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...

Homework Statement Question: Two trains on separate tracks move toward one another. Train #1 has a speed of 130 km/hr and train #2 a speed of 90km/hr. Train 2 blows its horn, emitting a frequency of 500 Hz. What frequency is heard by the engineer on train #1? Homework Equations This is...

I have a question that has been bugging me for a while. You see, I have a predisposition of trying to visualize everything that I learn. I have no problem visualizing space-time, black-holes distorting space-time, the universe expanding, etc..., but when it comes to the Doppler Effect I want to...

While studying the Doppler effect at school, it struck me as strange that the following two problems have different solutions: a) you are moving at 40 m/s toward a source that is making a sound with a frequency of 1000 Hz. What frequency do you hear? (speed of sound= 340 m/s) b) The...

Homework Statement A policeman with a very good ear and a good understanding of the Doppler effect stands on the shoulder of a freeway assisting a crew in a 40-mph work zone. He notices a car approaching that is honking its horn. As the car gets closer, the policeman hears the sound of the...

Does the amplitude of a wave changes when the source is moving? I am mainly interested in waves in a medium (e.g. sound, water...) No text about Doppler effect I have found mentions anything about the amplitude so I guess it does not change. However in the case if the speed of the source...

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...

Hi I keep reading that an atom cannot be cooled to v=0 because of random recoil from spontaneous emission, i.e. a random walk in momentum space. If it is a random walk, then - on average - we don't have any net motion, i.e. we stay at the initial position. This also holds in momentum...

Frequency changes relative to the observer due to the doppler effect. Does wavelength?

Homework Statement A tuning fork vibrating at 506 Hz falls from rest and accelerates at 9.80 m/s2. How far below the point of release is the tuning fork when waves of frequency of 488 Hz reach the release point? (Take the speed of sound in air to be 343 m/s).Homework Equations...

Homework Statement Bird A and B are flying towards each other Bird B at 20m/s Bird A at 15m/s and screeches with a frequency of 3200 Hz what does bird B perceive? Homework Equations the speed of sound is 343m/s Fobserver==Fsource((vsound+vobserver)/(vsound+vsource) The Attempt...

Doppler effect told us that the frequency and wavelength changed but not the speed of wave if the transmitter or receiver is moving. Could I interpret Doppler Effect as follow: Frequency/wavelength change for different observers, however, the speed of wave is constant for all observers. If...

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...

So a factory whistle emits a sound at 875Hz. The temperature of the air is 25.9oC. What frequency will be heard by an observer in a car traveling at 27m/s away from the source i know this is a two step problem but i have no idea where to start! anyone lead me in the right direction?

vw= Velocity of Wave vm= Velocity of Wave Source fw= Frequency of the Wave fd= Frequency of the Wave relative to Detector as Wave Source is also moving q= Infinity For the wave frequency detected by a detector at rest as the wave source* is moving towards it, there is: fd=( vwfw )/(...

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 A truck moving at 36 m/s is overtaken by a police car moving at 45 m/s in the same direction. If the frequency of the siren relative to the police car is 500 Hz, what is the frequency heard by an observer in the truck as the police car approaches the truck? (The speed of...

Here are some different descriptions of Doppler shifts: 1. The gamma rays in the Pound-Rebka experiment were Doppler shifted. 2a. We make a cosmological model using coordinates in which an object moving with the Hubble flow has a zero coordinate velocity, so all galaxies are "at rest." An...

Homework Statement Estimate the width of a 21cm spectral line produced by an interstellar cloud of atomic hydrogen with a temperature of 300K. Homework Equations From wiki (link below), I found an equation for full width at half maximum, relating it to Boltzmann constant...

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...

I found a question in a Maltese physics past paper dealing with the doppler effect. I managed to figure out the part dealing with the effect of motion of the wave source, but i was asked this: How does The Doppler Effect show us the difference between galaxies that are near and those that are...

I'd like to know how to build a short-rang (maybe 30-100 ft) Doppler radar. I will use the radar to pinpoint any object it sees on a map. This radar will be used with a PC or iPhone, so the unit does not make any calculations whatsoever. Also, I'd like the unit to be as small as possible.

my query is : The electric and magnetic fields don’t squeeze or stretch then how is Doppler Effect of light possible? In the phenomenon of Doppler Effect, light emitted from a moving source is detected to have different frequency. If this is taken on terms of detecting the no. of waves...

Homework Statement A siren has two loud speakers attached to a rotating disk. The disks radius is 3m. The speakers emit a sound frequency of 300 Hz.(Speed of sound in air is 344 m/s) A)How fast does the disk need to spin for an observer standing some distance away to perceive two frequencies...

Was it considered that the force of gravity could vary according to the redshift equation? 1+z=\frac{1+v \cos (\theta)/c}{\sqrt{1-v^2/c^2}} If those who consider this are right, then it would imply that an object leaving a gravitational system would experience a slight decrease in the...

I have a question about of light waves. Moving at high speeds toward or away from visible light could be the difference of experiencing that light as violet or red. Of course this experience is due to the photoreceptors in the eye seemingly experiencing a shorter or longer wavelength. My...

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...

Im trying to solve back for Jupiters effect on the suns orbital velocity. I've looked up the asnwer and its 12.7 m/s and the formula I have for this is http://en.wikipedia.org/wiki/Doppler_spectroscopy v = SQR (Gm*/r) where G is Grav constant M is the mass of the star (planets mass is...

Homework Statement A star is moving away from Earth at a speed of 2.4 x 10^8 m/s. Light of wavelength 480 nm is emitted by the star. What is the wavelength as measured by an Earth observer?Homework Equations fo=fs(1 - vrel/c) I substracted because they the star is moving away from the earth...

Homework Statement Not really a homework, but i did run across it while attempting some questions. Was reading through the derivations of relativistic doppler effect on EM waves and was reading wiki(http://en.wikipedia.org/wiki/Relativistic_Doppler_effect" when i came across something...

The problem: I have to answer a question about the Doppler effect using the formula attached. I know i have to solve for Vw, but I get Vw/Vw=(Fd/Fs)(-Fs) and I am possitive that's not right, can someone please help me out?? Thankyou

A stationary destroyer is equipped with sonar that sends out pulses of sound at 30.000 MHz. Reflected pulses are received from a submarine directly below with a time delay of 60 ms at a frequency of 29.958 MHz. (a) If the speed of sound in seawater is 1.55 km/s, find the depth of the...

Homework Statement A sound source moves at a constant velocity. A listener is standing at a distance L away from it. Given that the source moves in a straight line at a right angle to the listener and starts closest to the listener (ie at t=0) deduce an expression for the frequency heard by the...

Homework Statement I read that when a body approaches a stationary one which emits radar waves, the wavelength λ2 of the returned waves is longer than λ1, the wavelength of the emitted ones, but I get the opposite. I suppose this is true for sound waves also. See picture. The Attempt at a...