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Spund sources

  • Thread starter jono90one
  • Start date
  • #1
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Homework Statement


A sound source moves at a constant velocity. A listener is standing at a distance L away from it. Given that the source moves in a straight line at a right angle to the listener and starts closest to the listener (ie at t=0) deduce an expression for the frequency heard by the listener in relation to time.


Homework Equations



fl=fs(v/(v-vs))
where l is listener and s is source

The Attempt at a Solution


It's obviously Doppler effect related.
So far I’ve done T=1/fs
And gotten
fl=v/T(v-vs)

But unsure how to get L into the equation.
Surely VT is the distance travelled by the wave and vsT is λs. Is there any orientation where L can be introduced? Or is this version correct?
 

Answers and Replies

  • #2
take in the velocity component of the source away from the observer at each instant of time in the governing equation.
 
  • #3
28
0
(edit) So you mean f=v/T(vs-v)??
 
Last edited:
  • #4
No
O(t=0)----------------------->vt(point A)(source)
|
|
|
|L
|
|
Point B(you)
I want you to find the component of source’s(A) velocity
Along the line joining point A & point B at an instant t
And plug that velocity into your equation for vs.
 

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