In really stormy weather and with the right conditions, the sky would dump a bun

Question

In really stormy weather and with the right conditions, the sky would dump a bunch of hail, making the roads rather hazardous. A choir director was driving his car in these conditions and going a tad fast under the circumstances. His car began to slip on the balls of ice in the road towards two music students walking in front of him, so he leaned on his horn to warn the students to jump out of the way. Since he has career in music, his car horn is set to emit a frequency at exactly Tenor C – 523 Hz. The students have perfect pitch and are able to determine that the frequency that they hear is now 554 Hz (a semitone sharp for any musicians in the room). Since they have also taken Physics with Algebra, they were able to determine the choir director’s speed. What was that speed? Not having learned his lesson, the director passed the student and continued on his way at the same speed. What frequency did the students hear this time? (No, it is not 492 Hz.) The students walked away discussing whether or not to report this instance of reckless driving to the superintendent

Explanation / Answer

f=523Hz, f'' =554Hz

Stationary detector, source moving towards detector

=>f''/f =(V-0)/(V-Vs)

=>(340/(340-Vs) =1.059

=>340 =360.15-1.059*Vs =>1.059*Vs =20.15 =>Vs =19m/s

b)Soucre moving away, detector stationary

=>f''/f =(V-0)/(V+Vs) =340/(340+19) =495.32Hz

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