the pitch of a race cars motor sounds higher as it approaches an observer and sound slower when it travels away this is an example of which of the following?
This phenomenon is an example of the Doppler effect.
The phenomenon described is known as the Doppler effect.
The phenomenon you are referring to is known as the Doppler effect. The pitch, or frequency, of a sound wave appears higher when the sound source approaches an observer and lower when it moves away. This effect can be observed with various types of sounds, including the motor sound of a race car.
To understand why this happens, let's break it down:
1. When a race car approaches an observer, the sound waves it emits get compressed. This means that the distance between successive wave peaks, or the wavelength, appears shorter to the observer. As a result, the frequency of the sound wave increases, and we perceive it as a higher pitched sound.
2. Conversely, when a race car moves away from an observer, the sound waves get stretched out. Consequently, the wavelength appears longer to the observer, and the frequency of the sound wave decreases. This shift in frequency leads us to perceive the sound as a lower pitch.
The Doppler effect is not only applicable to sound waves but also to other types of waves, such as light waves and radio waves. Its principles can be used to explain various phenomena in physics, including the redshift observed in cosmology and the change in pitch of emergency vehicle sirens as they pass by.