Question

You are driving along a highway at 22.0 m/s when you hear the siren of an ambulance traveling in the opposite direction on the other side of the highway. When the vehicle is approaching you, you hear the frequency of the siren as 2800 Hz, but when it is past you the frequency becomes 2140 Hz. What is the speed of the ambulance? The speed of sound in air is 345.0 m/s.

Answer 1

Do you know the formula for Doppler Effect ??

Answer 2

My prof gave me 5 but I must be using it wrong this is the only question I keep messing up..

Answer 3

And I can't answer the question after is that is easy until I get this :/

Answer 4

Aren't two variables missing? speed of source and frequency of the source?

Answer 5

If you can write the the equation for both the cases, we'll have two equations and two unknown variables.

Beyond that, it is just elementary mathematics :)

Answer 6

Got this for the formulas.. (it's the pencil)

Answer 7

oops bottom on of the second equation is supposed to be a positive I think

Answer 8

Why did you make four cases ??

Answer 9

That's the formula my prof gave me idk...

Answer 10

I made two I thought, one for the before passing and one for after?

Answer 11

The two cases at the top of the page correctly represents the question.

Answer 12

so since fs is the same for both of them i'm assuming that has something to do with combining them right?

Answer 13

fs and Vs are two unknowns..

We can simply divide the two equations to eliminate fs and then solve for Vs

Answer 14

by each other?? crap it closes in 10 mins :O

Answer 15

Makes sense since fs/fs would be one

Answer 16

Nevermind I give up. Just had a Statics Midterm followed by Law class and missed supper so my brain is mush. The 8:00 am mechanics class doesn't help -_-

Answer 17

??