The Doppler effect demonstrated by a moving fire truck emitting sound waves, with changes in frequency observed by a stationary listener.

It looks like you've uploaded an image of a worksheet about the Doppler Effect, which is a phenomenon in physics where the frequency of a wave (like sound or light) changes for an observer moving relative to the source.

Let’s go through the questions and solve them one by one, with explanations.

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Question 1:

When an automobile moves towards a listener, the sound of its horn seems relatively...

- A. Low pitched
- B. High pitched

✔ Answer: B. High pitched

Explanation:
As the car moves toward the listener, the sound waves are compressed (wavelength decreases), resulting in a higher frequency. Higher frequency means a higher pitch. This is the Doppler Effect in action.

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Question 2:

When the automobile moves away from the listener, its horn seems...

- A. Low pitched
- B. High pitched

✔ Answer: A. Low pitched

Explanation:
As the car moves away, the sound waves are stretched out (wavelength increases), leading to a lower frequency and thus a lower pitch.

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Question 3:

The changed pitch of the Doppler effect is due to changes in...

- A. Wave speed
- B. Frequency

✔ Answer: B. Frequency

Explanation:
The pitch we hear depends on the frequency of the sound wave. The Doppler Effect causes a change in the observed frequency due to motion, not because the wave speed changes (wave speed depends on the medium, like air). So, it's frequency that changes, not speed.

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Question 4:

Circle the letter of each statement about the Doppler Effect that is true.

Let’s evaluate each:

A. It occurs when a wave source moves toward an observer
✔ True – This causes a higher frequency (blueshift).

B. It occurs when an observer moves toward a wave source
✔ True – Even if the source is stationary, motion of the observer can cause a Doppler shift.

C. It occurs when a wave source moves away from an observer
✔ True – Causes lower frequency (redshift).

D. It occurs when an observer moves away from a wave source
✔ True – Also results in a lower observed frequency.

So all four statements are true.

✔ Answer: A, B, C, D

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Question 5:

True / False: A moving wave source does not affect the frequency of the wave encountered by the observer.

✘ False

Explanation:
This is false. A moving wave source does affect the frequency observed by the observer — this is exactly what the Doppler Effect describes. The frequency changes depending on whether the source is approaching or receding.

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Question 6:

True / False: A higher frequency results when a wave source moves towards an observer.

✔ True

Explanation:
Yes, when the source moves toward the observer, the waves are compressed, leading to higher frequency. This is why a siren sounds higher-pitched as it approaches.

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✔ Final Answers Summary:

1. B. High pitched
2. A. Low pitched
3. B. Frequency
4. A, B, C, D (All are true)
5. False
6. True

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Let me know if you'd like a visual explanation or a diagram to go along with this!