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roam
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Homework Statement
An ambulance is traveling at 72.0 km/h towards an intersection. Jim stops his car to give way to the ambulance as shown in the diagram below. In the diagram, the angle θ = 41.0 °.
The ambulance has a siren which produces sound at a frequency of 2.1 kHz. Assume the speed of sound in air is 335.0 m/s.
[PLAIN]http://img693.imageshack.us/img693/7959/amburightjimrest.gif
What is the doppler shift (Δf = f ′ – f ) heard in the siren sound by Jim, when Jim and the ambulance are positioned as shown on the diagram above?
(correct answer: 0.0991 kHz)
Homework Equations
General Doppler-shift expression: [tex]f'=\left( \frac{v+v_o}{v-v_s} \right)f[/tex]
The Attempt at a Solution
[tex]f'=\left( \frac{v+v_o}{v-v_s} \right)f= \left( \frac{335}{335-72} \right)2.1=2.62[/tex]
f'-f=2.62-2.1= 0.52
Why am I not getting the right answer? Does this have something to do with the angle? All the examples in my textbook deal with situations where the observer or the source are moving directly toward one another, there are no examples with angles. Any help is appreciated.
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