Doppler effect

  • Thread starter amit25
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Homework Statement


Man travels down the highway in his car whistling middle C
A policeman has a defective radar gun but passed a physics course. He hears the
pitch change from D(294 Hz) immediately above middle C(262Hz) to A#(233Hz) immediately below
middle C as the car passes.
a) How fast is Professor Zoom traveling?
b) Should Professor Zoom get a ticket? if speed limit is 100km/hr


Homework Equations


f = frequency of source
f1 = frequency at observer
c = speed of sound (330m/s)
v = velocity of observer
v1 = velocity of source

source moving towards stationary observer.
f x c/(c-v1) = f1

source moving away from stationary observer.
f x c/(c + v1) = f1

The Attempt at a Solution


So for source moving towards stationary observer

f x c/(c-v1) = f1

262(330)/330-v1=294
v1=36m/s

source moving away from stationary observer.
f x c/(c + v1) = f1

262(330)/330+v1=233
v1=41m/s

I just want to know if im on the right track, or what am I doing wrong? and do i add those two velocity together? when you convert those velocities into km/h they surpass 100km/hr so I said that yes he does get a ticket. Help please :) im a little lost...
 

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