A train moving at 29.5m/s passes a platform, sounding a horn with frequency of 1560Hz. Find the frequency?

Question

heard by an observer on the platform as the train approaches and as it recedes.

Answer 1

the Doppler effect general equation is:

f'=((v+vo)/(v-vs))*f

where v is the speed of the waves (340 m/s for sound)
vo is the velocity of the observer
vs is the velocity of the source
f is the frequencey at the source
f' is the frequency at the observer

approaching:

f'=(340/(340-29.5))*1560

Receeding
f'=(340/(340+29.5))*1560

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