How Does Motion Affect Sound Frequency and Wavelength Calculation?

[Ronaldo21]

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
please help!

 

[Delphi51]

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.

 

[Ronaldo21]

for number 1, we're trying to find distance arent we? not velocity.
and for 2, well i converted km/h to m/s.

 

[Delphi51]

for number 1, we're trying to find distance arent we? not velocity.

Yes, so solve the formula for λ.