A source of frequency f moves through still air with speed uₛ < v. Which statements are correct?

Select all that apply

• Option A

  The wavelength in front is (v-uₛ)/f.

• Option B

  The wavelength behind is (v+uₛ)/f.

• Option C

  The source continues to oscillate at frequency f in its own frame.

• Option D

  A stationary observer in front of the approaching source hears a frequency greater than f.