Gah, I accidentally logged out. The question I had posted was: An ambulance siren creates a 1200 Hz wave. What frequency will be heard if:
The ambulance is moving away from you at 35 m/s?
Toward you at 25 m/s?

Question

Gah, I accidentally logged out. The question I had posted was: An ambulance siren creates a 1200 Hz wave.  What frequency will be heard if:
The ambulance is moving away from you at 35 m/s?
Toward you at 25 m/s?

anonymous · Answer

From the equations of Doppler effect, 
f'=(v/v+u)f
if the source is moving away from you &
f'=(v/v-u)f
if it moves towards you
v=speed of sound 
u=speed of the source
f=actual frequency
f'=perceived frequency

anonymous · Answer

so the answers are 1088 Hz & 1337.7 Hz respectively (JUST FOR CHECKING)