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11th grade The Doppler effect worksheet

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The Doppler effect

Grade 11 Science Worksheet

NameDate

Circle the best answer, or write your answer on the line.

  1. A 400 Hz train horn approaches at 20 m/s. With sound at 343.3 m/s in 20 °C air, what frequency does a listener ahead hear, to the nearest tenth, Ari?

  2. A 1000 Hz toy buzzer on a cart approaches at 5 m/s. With sound at 343.3 m/s in 20 °C air, what frequency does a listener ahead hear, to the nearest tenth, Bo?

  3. Read this first

    A 400 Hz train horn passing at different speeds, in 20 °C air (worked out with 343.3 m/s for sound)

    Train speed (m/s)Heard approaching (Hz)Heard moving away (Hz)
    10412388.7
    20424.7378
    30438.3367.9

  4. Using the table, how does the train's speed change the shift, Jun?

    • Speed makes no difference
    • Faster trains make smaller shifts
    • Faster trains make bigger shifts

  5. Using the table, what does a listener hear as a 20 m/s train moves away, Kira?

    • 400 Hz
    • 378.0 Hz
    • 424.7 Hz

  6. Using the table, by about how many hertz does the pitch drop as a 10 m/s train passes, Luz?

    • About 400 Hz
    • About 12 Hz
    • About 23 Hz

  7. Light from a distant galaxy is shifted toward longer, redder wavelengths. What does that show, Milo?

    • The galaxy is moving toward us
    • The galaxy is cooling down
    • The galaxy is moving away

  8. A star is moving toward us. Which way is its light shifted, Noah?

    • It isn't shifted, since light is so fast
    • Toward red, longer wavelengths
    • Toward blue, shorter wavelengths

  9. A listener on a moving train passes a horn that stands still beside the track. How does the horn sound while approaching it, Ren?

    • Higher than its own pitch
    • Lower than its own pitch
    • The same, since the horn isn't moving

  10. After passing the still horn, the listener's train moves away from it. How does the horn sound now, Tala?

    • Lower than its own pitch
    • Silent
    • Higher than its own pitch

  11. A buzzer rides on a cart, and a listener rides beside it at the same speed. What shift does the listener hear, Zee?

    • None
    • A higher pitch
    • A lower pitch
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11th grade The Doppler effect worksheet – printable
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About this worksheet

The Doppler effect. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can explain the Doppler effect from bunched and spread wave fronts. An approaching source sounds higher, one moving away sounds lower, and the pitch drops as it passes.
  • I can tell the source's own frequency, which never changes, from the frequency heard. I can tell pitch from loudness.
  • I can use f = f₀v ÷ (v − vₛ) for an approaching source and f₀v ÷ (v + vₛ) for one moving away, with sound at 343.3 m/s in 20 °C air. I know a moving listener also hears a shift.
  • I can read redshift (moving away) and blueshift (approaching) in light, and name uses: weather radar, radar speed sensors and astronomy.

Standard: none (TX, FL)

Words to know

Doppler effect: A change in the frequency heard because the source or listener moves

source: The object making the waves, like a horn

redshift: Light stretched to longer wavelengths because its source moves away

blueshift: Light squeezed to shorter wavelengths because its source approaches

pitch: How high or low a sound is; set by frequency

Common mistakes

Your child added the frequencies. The shift is the heard frequency minus the source's frequency.

Your child used the wrong sign. An approaching source bunches the waves, so use v − vₛ; a source moving away spreads them, so use v + vₛ.

Your child thought the source itself changes pitch. The source keeps its frequency; the listener hears a shifted one because of the motion.

Questions parents ask

What is the most common mistake with the doppler effect?

Your child added the frequencies. The shift is the heard frequency minus the source's frequency.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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