Free Printable T2 PS: Doppler Effect

1.

Is the following statement true/false regarding Doppler Effect:

"The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source."

a)

True

b)

False

2.

An ambulance is moving towards a stationary listener at a constant speed of 30 m∙s-1 . The siren of the ambulance emits sound waves having a wavelength of 0,28 m. Take the speed of sound in air as 340 m∙s-1

Calculate the frequency of the sound waves emitted by the siren as heard by the ambulance driver.

a)

$1\ 213\ \ Hz$

b)

$1\ 214,29\ \ Hz$

c)

$1\ 215\ \ Hz$

3.

An ambulance is moving towards a stationary listener at a constant speed of 30 m∙s-1 . The siren of the ambulance emits sound waves having a wavelength of 0,28 m. Take the speed of sound in air as 340 m∙s-1 .

Calculate the frequency of the sound waves emitted by the siren as heard by the listener.

Choose the correct answer.

a)

1331,80\ Hz

b)

$1\ 332\ Hz$

c)

$1\ 331,7\ Hz$

4.

An observation of the spectrum of a distant star shows that it is moving away from the Earth.

Choose, in terms of the frequencies of the spectral lines, the correct answer how it is possible to conclude that the star is moving away from the Earth.

a)

The spectral lines of the star are be shifted towards the lower frequency end, which is the red end of the spectrum.

b)

The spectral lines of the star should be shifted towards the lower frequency end, which is the blue end of the spectrum.

5.

Refer to the figure alongside. Is the sound source moving TOWARDS or AWAY FROM the listener?

Answer only with AWAY or TOWARDS.

(a)

6.

Use the information in the table to calculate the speed of sound during the investigation.

Choose the correct answer.

a)

336\ m\cdot s^{-1}

b)

$336,15\ m\cdot s^{-1}$

c)

$337\ m\cdot s^{-1}$

7.

The spectral lines of a distant star are shifted towards the longer wavelengths of light. Is the star moving TOWARDS or AWAY FROM the Earth?

Answer with only TOWARDS or AWAY.

(a)

8.

The siren of a stationary ambulance emits a note of frequency $1130\ Hz$ . When the ambulance moves at a constant speed, a stationary observer detects a frequency that is $70\ Hz$ higher than that emitted by the siren.

Is the ambulance moving towards or away from the observer?

Answer with only TOWARDS or AWAY.

(a)

9.

The siren of a stationary ambulance emits a note of frequency $1130\ Hz$ . When the ambulance moves at a constant speed, a stationary observer detects a frequency that is $70\ Hz$ higher than that emitted by the siren.

a)

20\ \ m\ \cdot s^{-1}

b)

$20,01\ m\cdot s^{-1}$

c)

$21\ m\cdot s^{-1}$

10.

The siren of a stationary police car emits sound waves of wavelength $0.55\ m$ .

With its siren on, the police car now approaches a stationary listener at constant velocity on a straight road. Assume that the speed of sound in air is $345\ m.s^{-1}$

Will the wavelength of the sound waves observed by the listener be GREATER THAN, SMALLER THAN or EQUAL TO $0.55\ m$ ?

(a)

11.

The siren of a stationary police car emits sound waves of wavelength $0.55\ m$ .

With its siren on, the police car now approaches a stationary listener at constant velocity on a straight road. Assume that the speed of sound in air is $345\ m.s^{-1}$ .

Name the phenomenon observed.

(a)

12.

An ambulance approaches a stationary observer at a constant speed of $10.6\ m.s^{-1}$ , while its siren produces sound at a constant frequency of $954.3\ Hz$ . The stationary observer measures the frequency of the sound as $985\ Hz$ .

Name the medical instrument that makes use of the Doppler effect.

(a)

13.

An ambulance approaches a stationary observer at a constant speed of $10,6\ m.s^{-1}$ , while its siren produces sound at a constant frequency of $954,3\ Hz$ . The stationary observer measures the frequency of the sound as $985\ Hz$ .

a)

340\ m\cdot s^{-1}

b)

$340,1\ m\cdot s^{-1}$

c)

$339\ m\cdot s^{-1}$

14.

An ambulance approaches a stationary observer at a constant speed of $10,6\ m.s^{-1}$ , while its siren produces sound at a constant frequency of $954,3\ Hz$ . The stationary observer measures the frequency of the sound as $985\ Hz$ .

How would the wavelength of the sound wave produced by the siren of the ambulance change if the frequency of the wave were higher than $954,3\ Hz$ ? Write down only INCREASES, DECREASES or STAYS THE SAME.

(a)

15.

A train approaches a station at a constant speed of $20\ m.s^{-1}$ with its whistle blowing at a frequency of $458\ Hz$ . An observer, standing on the platform, hears a change in pitch as the train approaches him, passes him and moves away from him.

Calculate frequency of the sound that the observer hear while the train is approaching him. Use the speed of sound in air as $340\ m.s^{-1}$ .

a)

486,63\ \ Hz

b)

$487\ \ Hz$

c)

$458\ \ Hz$

16.

A train approaches a station at a constant speed of $20\ m.s^{-1}$ with its whistle blowing at a frequency of $458\ Hz$ . An observer, standing on the platform, hears a change in pitch as the train approaches him, passes him and moves away from him.

How will the observed frequency change as the train passes and moves away from the observer? Write down only INCREASES, DECREASES or REMAINS THE SAME.

(a)

17.

A train approaches a station at a constant speed of $20\ m.s^{-1}$ with its whistle blowing at a frequency of $458\ Hz$ . An observer, standing on the platform, hears a change in pitch as the train approaches him, passes him and moves away from him.

How will the frequency observed by the train driver compare to that of the sound waves emitted by the whistle? Write down only GREATER THAN, EQUAL TO or LESS THAN.

(a)

18.

A fire truck, with its siren on, is moving at $20\ m.s^{-1}$ towards a burning building. A person standing next to the road with a detector, measures the frequency of the sound emitted by the siren to be $450\ Hz$ . The measured frequency is HIGHER than the frequency of the sound emitted by the siren.

Is the fire truck moving toward or away from the person?

(a)

19.

A fire truck, with its siren on, is moving at $20\ m.s^{-1}$ towards a burning building. A person standing next to the road with a detector, measures the frequency of the sound emitted by the siren to be $450\ Hz$ . The measured frequency is HIGHER than the frequency of the sound emitted by the siren.

Why the registered frequency is higher?

a)

The truck is moving towards the bystander

b)

The truck moving at high speed.

20.

A fire truck, with its siren on, is moving at $20\ m.s^{-1}$ towards a burning building. A person standing next to the road with a detector, measures the frequency of the sound emitted by the siren to be $450\ Hz$ . The measured frequency is HIGHER than the frequency of the sound emitted by the siren.

Calculate the frequency of the siren if the speed of sound in air is $340\ m.s^{-1}$ .

a)

423,53\ \ Hz

b)

$423\ \ Hz$

c)

$424\ \ Hz$

21.

The whistle of a train emits sound waves of frequency $2\ 000\ Hz$ . A stationary listener measures the frequency of these emitted sound waves as $2\ 080\ Hz$ . The speed of sound in air is $340\ m.s^{-1}$ .

Is the train moving AWAY FROM or TOWARDS the stationary listener?

(a)

22.

The whistle of a train emits sound waves of frequency $2\ 000\ Hz$ . A stationary listener measures the frequency of these emitted sound waves as $2\ 080\ Hz$ . The speed of sound in air is $340\ m.s^{-1}$ .

a)

14\ m\cdot s^{-1}

b)

$13\ m\cdot s^{-1}$

c)

$13,08\ m\cdot s^{-1}$

23.

The whistle of a train emits sound waves of frequency $2\ 000\ Hz$ . A stationary listener measures the frequency of these emitted sound waves as $2\ 080\ Hz$ . The speed of sound in air is $340\ m.s^{-1}$ .

Will the frequency observed by a passenger, sitting in the train, be GREATER THAN, EQUAL TO or SMALLER THAN $2\ 000\ Hz$ ?

(a)

T2 PS: Doppler Effect

Total questions: 23

Worksheet time: 6hrs 45mins

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