A train whistling at constant frequency is moving towards a station at a constant speed V . train go

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14.Waves and Sound

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A train whistling at constant frequency is moving towards a station at a constant speed $V$. The train goes past a stationary observer on the station. The frequency $n'$ of the sound as heard by the observer is plotted as a function of time $t (Fig.)$ . Identify the expected curve

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B

C

D

Solution

Approaching source $n' = n\left[ {\frac{V}{{V – {V_S}}}} \right]$ constant

Receading source $n' = \left[ {\frac{V}{{V + {V_S}}}} \right]$ constant

Standard 11

Physics

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