A railroad train is traveling at 24.0 m/s in still air. The frequency of the not

ID: 2002178 • Letter: A

Question

A railroad train is traveling at 24.0 m/s in still air. The frequency of the note emitted by the locomotive whistle is 408 Hz .

a) What is the wavelength of the sound waves in front of the locomotive? (I've tried .83 and .9, both incorrect)

b) What is the wavelength of the sound waves behind the locomotive? (.784 is incorrect)

c) What is the frequency of the sound heard by a stationary listener in front of the locomotive?

d) What is the frequency of the sound heard by a stationary listener behind the locomotive?

Part A)

v = f

(344 + 24) = (408)()

= .968 m

Part B)

v = f

(344 - 24) = (408)()

= .842 m

Part C)

From the Doppler Effect

f' = f/(v/v - vs)

f' = 408(344)/(344 - 24)

f' = 408.5 Hz

Part D)

Again from the Doppler Effect

f' = f/(v/v + vs)

f' = 408(344)/(344 + 24)

f' = 355.2 Hz

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