Question

help me in this one part b)​

Answer 1

When a car approaches you the sound waves that reach you have a shorter wavelength and a higher frequency and when the car moves away from you the sound waves that reach you have a longer wavelength and lower frequency you hear a sound with a lower pitch. The doppler effect is observed because the distance between the source of sound and the observer is changing and if the source is moving away from the observer the observer perceives sound waves reaching him or her at a less frequent rate low pitch.