Question

If a car passes a pedestrian, a change in pitch is __________.

Answer 1

Given two questions:

1) If a car passes a pedestrian, a change in pitch is ______________. 
The answer is the change in pitch is perceived by the pedestrian since he is the one in a relatively constant position compared to the car passing. 

2) In the Doppler Effect lab, which statement best describes what you demonstrated about speed and pitch?

The answer is 'speed and direction affect pitch'.

Answer 2

The correct answers are as follows:

1. If a car passes a pedestrian, a change in pitch is PERCEIVED BY THE PEDESTRIAN.

The pitch of a sound refers to the quality of sound that makes it to be rated as a low or a high sound. Pitch varies with distance, that is, as one moves closer to a source of sound, the sound pitch increases and as one move away from the source of a sound, the pitch of the sound decreases. In the question given above, a change in pitch of the car sound will be perceived by the pedestrian, this is because, his position is constant relevant to that of the passing car. As the car moves away the sound pitch will decreases.

2. The correct answer is this: SPEED AND DIRECTION AFFECT PITCH.

Doppler effects refers to the increase or decrease in the pitch of a sound as one move towards or away from a sound. This change in sound is due to changes in the frequency of the sound. Speed and direction are two factors that affect the pitch of a sound.