Posted by Sher on .
A car horn is pitched at 520 Hz. The car travels along a straight road at a speed of 25 m/s. towards an observer walking at 2 m/. The speed of sound is 334 m/s. Calculate the frequency heard by the observer when:
(a) the car is moving towards the observer

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Elena,
http://en.wikipedia.org/wiki/Doppler_effect
http://hyperphysics.phyastr.gsu.edu/hbase/sound/dopp.html 
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Sher,
Can you give me the equation instead i'm still confused?

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bobpursley,
The equation is listed on both those sources, and you need to memorize it.

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Sher,
so which one is it? all of them are on both

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Elena,
I can’t understand the direction of Observer motion (towards or from the car?).
If the car and observer move towards each other,
their relative speed is 252 =23 m/s, then
f=f₀/[1v/c)] =
=520/[123/334] = 558.5 Hz
If they move in the same direction v =25+2 = 27 m/s, then
f=f₀/[1v/c)] =
=520/[127/334] = 565.7 Hz
If the car is moving FROM the observer
f=f₀/[1+ v/c)]
f= 520/[1+ 23/334)] =486.5 Hz
f=520/[1+ 27/334)] =481.1 Hz