a.)At rest, a car's horn sounds at a frequency of 410 Hz. The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 381 Hz. What is the speed of the car?
b.)Is the cyclist ahead of or behind the car?
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Why are you posting all these questions under different names? Do you expect us to work them for you?
Use the doppler equation. I will be happy to critique if for you.
Why are you posting all these questions under different names? Do you expect us to work them for you?
Use the doppler equation. I will be happy to critique if for you.
b) Since the bicyclist hears a lower frequency, and the car moves faster, the car must be moving away. So the cyclist is behind the car.
a) Use the Doppler shift formula and solve for V. The rate at which they are separating is (2/3)V, where V is the car's speed.
Using this approximate equation that is valid when the speed is much less than the speed of sound:
(delta f)/f = 29/410 = (2/3)V/(speed of sound)
Solve for V
V = (3/2)(340 m/s)*(29/410) = 36 m/s
There is a more accurate formula you could use, that takes into account the speeds of both the bike and the car. I will leave this up to you.
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