Question 319696: A siren that has a normal frequency of 1500 hertz is approaching you at 80 mph. What is the pitch that you will hear? Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! You didn't specify a temperature or altitude to determine the speed of sound.
I'll use 700 mph as the speed of sound.
-----------------
Frequency
The equation for the observed frequency of sound when the source is traveling toward you is:
fo = fv/(v − vt)
where
fo is the observed frequency
f is the emitted frequency
v is the velocity of sound
vt is the velocity of the source toward you
v > vt (vt is less than v)
-------------
fo = 1500*700/(700 - 80)
fo =~ 1694 Hz
