Marching Band doppler effect with Beat Frequency.

[Ethan_Tab]

Homework Statement

Emma and Don are playing in a band. While emma is marching toward Don, Don tunes his instrument to match the note that emma is playing. When emma stops, don immediately notices a beat frequency of 5 Hz. If the speed of the sound is 330m/s what is the relationship between Emmas speed and the frequency she is emmiting?

Homework Equations

f_obs=f₀[(v)/(v+-v_source)]
Bear Frequency= |f₂-f₁|
v=ƒλ

The Attempt at a Solution

at the speed which emma is moving, her note due to the doppler effect is shifted to a higher pitch which is what don tunes his instrument too. when she stops, the frequency of emmas note drops by 5Hz, to the actual note which was truly being played. Thats all i understand... what's the best way to get started?

 

[Ethan_Tab]

Just to add to what I just said, we can represent that first part through

f_obs=f₀+5
therfore
f₀+5=f₀[(v)/(v-v_Emma)]

 

[Nathanael]

what is the relationship between Emmas speed and the frequency she is emmiting?

f₀+5=f₀[(v)/(v-v_Emma)]

Isn't that a relationship between Emma's speed and the frequency she's playing? So what's the problem?