Question

describe how the doppler effect explains why a siren has a lower pitch as a fire engine moves away from you. enter your answer in the space provided. 

Answer 1

Doppler effect is the increase (or decrease) in the frequency of sound, light, or other waves because of the relative motion between wave source and observer . The effect causes sudden change in pitch, which is noticeable in a passing siren, as well as the red shift seen by astronomers.

Answer 2

When a fire engine moves forward in speed , so the air will also hit the siren then the siren will make less sound because more sound will go backside. So , from far away less notice will be heared but in the backside of the engine the sound will be more powerful . Sorry for my language in writing