Physics Worksheet

🚨 Doppler Effect

Chapter: Waves · Level ★★☆ · Time: 30 min

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NameClassDate

After this worksheet you can

Understand: What is the Doppler Effect?Understand: Approaching SourceUnderstand: Receding SourceUnderstand: Doppler Effect for Sound

🧠 Section A · Concept Check ● BEGINNER 4 × 1 = 4

1A car horn sounds higher-pitched as the car approaches you. What does this indicate about the car's motion?

2A star's light is blueshifted. What does this suggest about its motion relative to Earth?

3Why does a passing train's whistle seem to drop in pitch right as it passes you?

4How do astronomers use the Doppler effect to study the expansion of the universe?

🧮 Section B · Problem Solving ● INTERMEDIATE 4 × 3 = 12

5Does the Doppler effect apply only to sound, or also to other types of waves?

6A weather radar uses the Doppler effect to detect storm movement. What is it actually measuring?

7If both the source and observer are stationary, does the Doppler effect occur?

8Why might a siren sound normal in pitch if it's moving directly sideways relative to you (not toward or away)?

🚀 Section C · Challenge ● CHALLENGE 2 × 2 = 4

9What happens to the observed frequency if the source moves toward the observer faster and faster?

10Why is the Doppler effect useful for police radar guns measuring vehicle speed?

💭 Reflection — the most useful thing I learned:

A ___/4 B ___/12 C ___/4 Total ___/20 Teacher's Signature Parent's Signature

✂ answer key — fold or cut before handing out

1 = It's moving toward you 2 = It's moving toward Earth 3 = The train transitions from approaching (compressed waves, higher pitch) to receding (stretched waves, lower pitch) right as it passes 4 = Widespread redshift observed in distant galaxies indicates they are generally moving away from us, providing evidence for cosmic expansion | 5 = It applies to all types of waves, including light and other electromagnetic waves 6 = The frequency shift of radar waves reflecting off precipitation, revealing the precipitation's motion relative to the radar 7 = No, the Doppler effect requires relative motion between source and observer 8 = There is little to no relative motion along the line connecting the source and observer, minimizing the Doppler shift | 9 = The observed frequency increases even more (a greater Doppler shift) 10 = The frequency shift of the reflected radar wave directly relates to the vehicle's speed relative to the radar gun