Question

The police car with its 300-Hz siren is moving away from the warehouse at a speed of 16.0 m/s .

What frequency does the driver of the police car hear reflected from the warehouse?

Use 344m/s for the speed of sound in air.

Answer 1

This is Doppler effect problem. Remember this one?

Answer 2

The equation? fL =v+vL/lambda

Answer 3

It's a little bit different from the one i know.
\[f_r=\frac{v\pm v_r}{v\pm v_s}f_s\]
I'm sorry but I have to leave now.

Answer 4

Its ok. And that equation looks familiar so yours is probably right

Answer 5

Someone Please Help!

Answer 6

286 Hz

Answer 7

Is it exactly 286 hertz? Because I only have one more attempt at this problem

Answer 8

Actually, I tried that earlier and it was wrong

Answer 9

Maybe with the reflection off the warehouse, it is less, because the warehouse "percieves" a lower frequency and reflects it back to the car so maybe this is the answer:
(344-2*(16))*300/344 = 272 Does this seem reasonable?

Answer 10

Is there any other possible answers?

Answer 11

I only have one try left so I want to make sure

Answer 12

That is the best I can think of without having to review a textbook on Doppler effect.
It seems the frequency is reduced twice, once traveling to the warehouse and again with the reflected soundwave. I think it is right.

Answer 13

ok thanks. I'll try it

Answer 14

Good luck!

Answer 15

Thanks!!! it worked. Do you think you can help me with another problem?

Answer 16

Okay, sure. What is it?

Answer 17

I'll close this and open a new question