IB Physics Quiz: Apply Doppler Effect

Light from a distant galaxy has an observed hydrogen-alpha spectral line at 659.3 nm. The rest wavelength of this line is 656.3 nm. What is the approximate speed of the galaxy relative to Earth? (The speed of light, c = 3.00 × 10⁸ m s⁻¹)

A stationary ambulance emits a sound from its siren at 800 Hz. A person on a bicycle travels towards the ambulance at 20.0 m s⁻¹. What frequency does the cyclist hear? (The speed of sound in air = 340 m s⁻¹)

The spectral lines from a distant, rotating star are observed. How does a single absorption line from the star's spectrum appear compared to the same line from a stationary laboratory source?

A stationary police radar gun emits microwaves of frequency f. The waves reflect from a car approaching at speed u. The reflected waves are detected by the gun. The speed of the waves is c. Given that u ≪ c, what is the approximate frequency difference between the emitted and detected waves?

A small sound source is attached to the edge of a rotating turntable, moving in a horizontal circle at a constant speed. A stationary observer is located far away, in the same plane as the turntable. How does the frequency heard by the observer vary?

A bat flies toward a stationary wall at speed vₑ. It emits an ultrasound pulse of frequency f₀. The pulse reflects off the wall and returns to the bat. What is the frequency fₑ of the echo detected by the bat? (The speed of sound is vₛ).

A car's horn emits a sound at 425 Hz. When the car is moving directly away from a stationary observer, the observer detects a frequency of 400 Hz. What is the speed of the car? (The speed of sound in air = 340 m s⁻¹)

Two identical tuning forks produce a sound of 440 Hz. One tuning fork is stationary. The other is moved away from a stationary observer at a speed of 3.0 m s⁻¹. What is the approximate beat frequency heard by the observer? (The speed of sound in air = 340 m s⁻¹)

A stationary observer hears a sound from a source moving towards them at a constant speed, which is less than the speed of sound. Which statement correctly describes the properties of the sound waves between the source and the observer, compared to waves from a stationary source?

A sound source moving at speed u approaches a stationary observer, resulting in an observed frequency f_approach. The same source then moves away from the observer at the same speed u, resulting in f_recede. The source frequency is f₀. How does the magnitude of the frequency increase, Δf_approach = f_approach - f₀, compare to the magnitude of the frequency decrease, Δf_recede = f₀ - f_recede?

The light from Galaxy A has a redshift z = 0.01. The light from Galaxy B has a redshift z = 0.02. Redshift z is defined as Δλ/λ₀. What can be deduced about the galaxies, assuming the standard cosmological model?

A sound source S emits frequency f. The speed of sound is v. In Case 1, the source moves towards a stationary observer at speed u. In Case 2, the observer moves towards the stationary source at the same speed u. Let the observed frequencies be f₁ and f₂ respectively. Which statement is correct for all speeds 0 < u < v?

A police car's siren has a frequency of 600 Hz. The police car is travelling at 40 m s⁻¹ and chasing a truck travelling in the same direction at 30 m s⁻¹. What frequency does the driver of the truck hear? (The speed of sound in air = 340 m s⁻¹)

A weather radar system operating at $10 \text{ GHz}$ detects precipitation moving toward the station. If the received signal shows a frequency shift of $+67 \text{ Hz}$, and electromagnetic waves travel at $3.0 \times 10^8 \text{ m/s}$, what is the speed of the precipitation?

A police car traveling at $30 \text{ m/s}$ approaches a stationary observer while its siren emits sound at $800 \text{ Hz}$. After passing the observer, the car continues at the same speed. If the speed of sound is $340 \text{ m/s}$, what is the difference between the frequencies heard by the observer before and after the car passes?

Two identical sound sources each emit $500 \text{ Hz}$ tones. Source A moves toward a stationary observer at $20 \text{ m/s}$ while Source B moves away from the same observer at $20 \text{ m/s}$. If the speed of sound is $340 \text{ m/s}$ and the sources are positioned so their waves interfere at the observer's location, what phenomenon occurs?

A train whistle emits sound at $600 \text{ Hz}$. An observer on a platform hears $648 \text{ Hz}$ as the train approaches and $558 \text{ Hz}$ as it recedes. Using these measurements, what can be determined about the speeds involved?

An ambulance with a siren frequency of $1200 \text{ Hz}$ is moving toward a building at $25 \text{ m/s}$. The sound reflects off the building and returns to a stationary observer positioned between the ambulance and building. If the speed of sound is $340 \text{ m/s}$, what frequency does the observer hear from the reflected sound?

A bat emits ultrasonic calls at $50 \text{ kHz}$ while flying at $15 \text{ m/s}$ toward a moth that is flying away at $5 \text{ m/s}$. The sound reflects off the moth and returns to the bat. If the speed of sound is $340 \text{ m/s}$, what frequency does the bat detect in the returning echo?

A star emits light with a characteristic wavelength of $656 \text{ nm}$ in its rest frame. An astronomer observes this wavelength to be $659 \text{ nm}$. If this shift is entirely due to the star's motion relative to Earth, what can be concluded about the star's radial velocity?