Question

in the doppler effect, when do you hear a high pitch and why?
you hear a high pitch when the car is moving away from you because the sound wave gets spread apart.
you hear a high pitch when the car is coming towards you because the sound wave gets squished.

Explanation:

Pitch corresponds to sound wave frequency. When a sound source moves toward an observer, the sound waves in front of the source are compressed (squished), increasing their frequency. Higher frequency sound is perceived as a higher pitch. When the source moves away, waves spread out, lowering frequency and pitch.

Answer:

You hear a high pitch when the car is coming towards you because the sound wave gets squished.