# Dopple Effect

Classical Mechanics Level pending

Figure

An ambulance is running from A to B at a speed of 60 kilometres per hour with a siren of 880Hz as shown in the figure. Let the frequencies of the siren sound detected by the observer located at point O be $$v_{a}$$ and $$v_{b}$$ when the vehicle just passes point A and point B respectively. Point C is just to the north of point O and $$\vec{OC}=\vec{AC}=\vec{BC}=100m$$. The sound velocity is 340m/s.

What is the approximate value of $$v_{a}/v_{b} -1 ?$$

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