# Problem 53059. Siren frequency and Doppler effect.

The Doppler effect is described on OpenStax University Physics at https://openstax.org/books/university-physics-volume-1/pages/17-7-the-doppler-effect and in other sources.
Consider the Doppler effect for sound waves travelling in air. Use the equations in the OpenStax source (or equivalent information ) to model the Doppler effect.
A moving vehicle with a speed u, having a siren frequency, fs, approaches a static (fixed) observer and then passes the static observer. A siren , in this context, is also called a horn. The vehicle motion is modelled as straight-line motion.
One way of summarising the effect to the formula for two frequencies
or written in MATLAB syntax as
fh = fs *(c/(c-u))
fl = fs *(c/(c+u))
where fs is the frequency of a siren in Hz, c is the speed of sound in m/s , u is the speed of the moving vehicle in m/s, fh is the higher frequency in Hz as the vehicle approaches the stationary observer and the fl the lower frequency in Hz as the vehicle recedes from (passes) the observer.
Calculate the siren frequency, fs, to the nearest Hz. The function definition is
fs = findSirenFrequency ( c, u, fh, fl )
For example, if c = 345 m/s ; u= 30.5556 m/s ; fh = 877 Hz and fl =734 Hz then fs= 799 Hz. Assume fhfl and c > u.

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76.32% Correct | 23.68% Incorrect
Last Solution submitted on Nov 03, 2023