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Fundamental frequency

  • Thread starter Ronaldo21
  • Start date
  • #1
30
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Fundamental frequency!!

1. Ultrasound with a frequency of 4.079 MHz can be used to produce images of the human
body.If the speed of sound in the body is the same (1.97 km/s) as in salt water, what is the
wavelength in the body?
Answer in units of m.

and

2. On a day when the wind is blowing 49.5 km/h from east to west, a fire engine
moves toward you from the west at 112 km/h and you are heading toward the fire engine at
94.6 km/h. If the fire engine has a 587 Hz siren and the speed of sound is 340 m/s, what frequency do you hear?
Answer in units of Hz.
i converted them to m/s. (340-12-30.2777)*1170/(340-12-30.27777) but i think i did it wrong. idk. grr
and i DO NOT know how to do number 1
plz help!!
 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
10


The relationship between frequency and wavelength for any wave is
v = f*λ
That should take care of the first question.

What is your formula for the Dopplar effect in #2? The pattern of those numbers doesn't look quite right.
 
  • #3
30
0


for number 1, we're trying to find distance arent we? not velocity.
and for 2, well i converted km/h to m/s.
 
  • #4
Delphi51
Homework Helper
3,407
10


for number 1, we're trying to find distance arent we? not velocity.
Yes, so solve the formula for λ.
 

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