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What is the terminal speed of the paratrooper?

  • #1

Homework Statement


A helicopter drops a paratrooper carrying a siren that emits a 788 Hz audible signal. The microphone (reciever) on the plane monitors the signal from the transmitter as the paratrooper falls. Take the speed of sound in air to be 343 m/s and assume the paratroopers always remains below the helicopter. If the perceived frequency becomes constant at 412 Hz, what is the terminal speed of the paratrooper? Answer in units of m/s.


Homework Equations


Not sure... could you guys help me out.

Possibly Speed = wavelength * frequency ??


The Attempt at a Solution


Probably would need an equation first.
 

Answers and Replies

  • #2
199
0
Try and use your knowledge of the doppler effect for this.
 
  • #3
I don't really know much about it.

f' = f [(v+v1)/(v-v2)]

that's the equation. could you please walk me through this problem.
 
  • #4
199
0
Ok so the doppler effect is the apparent change in frequency of a wave due to the motion of the source or the observer.
So f' is the observed and f is the frequency of the source.

[tex] f' = \frac{fv}{v\pm u} [/tex]

where v is the speed of sound and u is the speed of the source or the observer.
If the source is approaching you it is v - u and if it is moving away it is v + u.
 
Last edited:
  • #5
Okay. That was very helpful. I got the answer of 313.03.

I submitted online and it is correct.

Thanks!
 
  • #6
199
0
No problem, happy to help.
 

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