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
http://en.wikipedia.org/wiki/Doppler_effect
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html
Can you give me the equation instead i'm still confused?
The equation is listed on both those sources, and you need to memorize it.
so which one is it? all of them are on both
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 25-2 =23 m/s, then
f=f₀/[1-v/c)] =
=520/[1-23/334] = 558.5 Hz
If they move in the same direction v =25+2 = 27 m/s, then
f=f₀/[1-v/c)] =
=520/[1-27/334] = 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
To calculate the frequency heard by the observer when the car is moving towards the observer, we need to use the Doppler effect formula. The formula for the observed frequency is given by:
f' = f * ((v + vo) / (v + vs))
Where:
f' is the observed frequency
f is the actual frequency of the source (520 Hz)
v is the speed of sound (334 m/s)
vo is the observer's speed (-2 m/s since the observer is walking towards the car)
vs is the source's speed (25 m/s since the car is moving towards the observer)
Now we substitute the given values into the formula:
f' = 520 * ((334 - 2) / (334 + 25))
= 520 * (332 / 359)
≈ 478.24 Hz
Therefore, the frequency heard by the observer when the car is moving towards them is approximately 478.24 Hz.