Question

Whether you are moving toward a siren, or the siren is moving toward you, the pitch of the siren changes as you move past. Which of the following best explains this?A.The amplitude of the sound waves in front of the siren are larger than those behind the siren.B.The sound waves in front of the siren bunch up, and those behind the siren spread out.C.Sirens always change frequency as they move past observers.D.Sirens always change wavelength as they move past observers.

Answer 1

The pitch of siren changes as the sound waves in the front of siren bunch up and those behind the siren spread out.

Thus, option B is correct.