An Observer Is Standing on the Platform of a Railway

question 7

Multiple Choice

An observer is standing on the platform of a railway station.A train goes through the station without stopping.If the frequency of the train whistle decreases by a factor of 1.2 as it approaches and then passes him,calculate the speed of the train (assume the speed of sound in air = 343 m/s) .

• A)112 km/hr
• B)31.2 km/hr
• C)56.0 km/hr
• D)62.0 km/hr
• E)122 km/hr

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