An ambulance is going away from me @ 40mph with a siren @ 1000Hz.Will I heat a higher or lower frequency

4 answers

It is going away so you hear a longer wavelength
so LOWER frequency
Use this simplified equation, which is short and dirty method to determine the answer to your question:

f=v/c*(f')

Where

v=-40mph=-17.88m/s
c=3 x 10^8 m/s
f'=1,000Hz

Just eyeballing the numbers, you should see a lower frequency, since v is negative.
I didn't know that you answered the question.
c=360m/s

I gave you the speed of light and not sound.