Question

The siren of a fire engine is heard in situations A,B, and C. Rank the pitch heard, from greatest to least, when the fire engine is traveling
A- Toward the listener at 30 km/h
B- Toward the listener at 50 km/h
C- Away from listener at 20 km/h
????

Answer 1

Do you know what the Doppler effect is?

Answer 2

Read about it here: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html

Answer 3

I am learning about it , just still confused

Answer 4

any help ?

Answer 5

I know that the least rank would be the 20km/h moving away

Answer 6

You can think of it like this.

The faster an object is moving towards you, the higher the frequency (pitch) will be. This is because the velocity of the vehicle change the wavelength (the spacing between the concentric circles in the diagrams in the link). Because the speed of sound is constant in the medium the frequency has to increase to maintain their relationship \(v=f*\lambda\)

Answer 7

ok so the higher the speed the higher the frequency of sound

Answer 8

yes, when it's moving towards you

Answer 9

and when it moves away from you ?

Answer 10

it's the opposite, when it moves away from you, the faster it's going away the lower the frequency will get.

Answer 11

so the ranking would be B>A>C !!1

Answer 12

yesss

Answer 13

You my friend deserve a metal!!!

Answer 14

Thank you very much!!

Answer 15

no problem at all !

Answer 16

can you be my fan ?

Answer 17

and if ever I have a question could you help me ?

Answer 18

and I will try to do the same =)

Answer 19

sounds good :)

Answer 20

can I ask you some more questions? Only if you have the time of course

Answer 21

I'm actually leaving (i'm still at school, kill me lol), so it'll have to be another time. sorry :S

Answer 22

ok np!!