Doppler Definition and 749 Threads

When a source emitting a sound of a specific frequency moves towards the face of a cliff at a speed. The frequency of the sound that reaches the cliff is for sure not the same as the frequency emitted from the source due to doppler effect. Will the frequency of the sound reflected by the cliff...

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...

So I'm having a hard time getting the second part of the problem, so could anyone help me An ambulance travels down a highway at a speed of 65.0 mi/h, its siren emitting sound at a frequency of 4.10 102 Hz. Take the speed of sound in air to be v = 345 m/s. What frequency is heard by a...

The Doppler Effect -- frequency of a bat reflected on wall Homework Statement A bat flies toward a wall, emitting a steady sound with a frequency of 22.0 kHz. This bat hears its own sound plus the sound reflected by the wall. How fast should the bat fly to hear a beat frequency of 190...

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)...

Homework Statement A sound source emits sounds of frequency 210 Hz that travel through still air at 340 m/s. The listener moves at 85 m/s relative to still air toward the stationary source. What is the wavelength of the sound between the source and the listener? Homework Equations f' = f[1+...

Hello everyone! I need some help with a Doppler effect/relative motion question. Homework Statement A whistle with a frequency of 1200 Hz is traveling south at a velocity of 30.0 m/s. You are traveling north away from the whistle at a speed if 18.0 m/s. If the speed of sound is 340 m/s, what...

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 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...

Homework Statement A sound source A and reflecting surface B move directly towards each other. Relative to the air the speed of source A is 29.9 m/s, the speed of the surface B is 65.8 m/s and the speed of sound is 329m/s. The source emits waves at frequency 1200 Hz as measured in the source...

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...

Homework Statement Pulse radar: Parameters: Carrier frequency: 5.3*10^9 Hz Pulse length: 20*10^-6s PRF: 30*10^6Hz Homework Equations The question is this: "100 pulses are reflected from a moving target and received by the radar. -What is the resolution of a speed...

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...

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...