A car horn emits a sound with a constant frequency of 405 Hz - Scottish Highers Physics - Question 6 - 2016

To determine the frequency of the sound heard by the student, we can use the Doppler effect formula for sound when the source is moving away from the observer:

$f' = f \frac{v}{v + v_s}$

Where:

• $f'$ = observed frequency
• $f$ = source frequency (405 Hz)
• $v$ = speed of sound (335 m/s)
• $v_s$ = speed of the source (28 m/s)

Substituting the values in:

$f' = 405 \frac{335}{335 + 28}$

Now, calculate:

1. Compute the denominator: $335 + 28 = 363$.
2. Now, calculate the fraction: $\frac{335}{363} \approx 0.9233$.
3. Finally, multiply by the source frequency: $f' \approx 405 \times 0.9233 \approx 374.03 \text{ Hz}$

Thus, the frequency of the sound from the horn heard by the student is approximately 374 Hz.