1. What is the Observed Frequency Calculator?

Definition: This calculator determines the frequency you hear (observed frequency) when either the sound source or you are moving.

Purpose: It helps kids understand the Doppler Effect - why sounds change when things move, like a passing ambulance siren.

2. How Does the Calculator Work?

The calculator uses the Doppler Effect formula:

Where:

• \( f_o \) — Observed frequency (Hz)
• \( v \) — Wave speed (343 m/s for sound in air)
• \( v_o \) — Observer's velocity (m/s)
• \( v_s \) — Source's velocity (m/s)
• \( f \) — Source frequency (Hz)

Explanation: When the source moves toward you, the frequency increases (higher pitch). When it moves away, the frequency decreases (lower pitch).

3. Fun Facts About Sound Frequency

Details:

• A passing ambulance siren changes pitch because of this effect
• Bats use this to detect flying insects
• Astronomers use it to measure star movements

4. Using the Calculator

Tips:

• Default wave speed is 343 m/s (sound in air)
• Positive velocity = moving toward each other
• Negative velocity = moving away from each other
• Try 440 Hz (musical A note) as source frequency

5. Frequently Asked Questions (FAQ)

Q1: Why does the sound change when things move?
A: When the source moves toward you, sound waves get bunched up (higher pitch). When moving away, they get stretched out (lower pitch).

Q2: What's a common example of this effect?
A: The changing pitch of a train whistle as it passes by is a perfect example!

Q3: Does this work with light too?
A: Yes! This is how astronomers know if stars are moving toward or away from Earth.

Q4: What happens if both source and observer move?
A: The calculator accounts for both movements - just enter both velocities!

Q5: Why is the default wave speed 343 m/s?
A: That's the speed of sound in air at room temperature (20°C or 68°F).