Chapter 21

Physics A First CourseVibrations, Waves, and Sound

Vibrations, Waves, and SoundSound

�21.1 Properties of Sound21.1 Properties of Sound

�21.2 Sound Waves

�21.3 Sound, Perception and Music

21A Investigation: The Properties of Sound

Key Question:

How do we know sound is a wave?

*Students read text section 21.1 AFTER Investigation 21A

21A Investigation Topics

� Identify the range of frequencies heard by the class.

� Conduct a survey and make a histogram of the results.results.

� Prove that sound is a wave.

� Demonstrate why beats occur.

� Find a mystery frequency.

Chapter 21.1 Objectives and Vocabulary

� Explain how pitch, loudness, and speed are related to waves.

� Explain the Doppler effect.

� pitch

� decibels

� acoustics

� subsonic� Explain the Doppler effect.

� Describe how sound is created and recorded.

� subsonic

� supersonic

� shock wave

� Doppler effect

Complex sound is made from many frequencies.

Common Sounds and their loudness(decibels)

Speed of Sound

�330 m/sec

�660 mile/hr�660 mile/hr

� faster in solids and liquids than in air

Chapter 21.2 Objectives and Vocabulary� reverberation

� Fourier's theorem

� Learn how sound is made and know the factors that affect the speed of sound.

� Know that the speed of � Know that the speed of sound changes in different materials.

� Recognize the importance of the wavelength of sound.

� Describe sound interactions.

� Compare the superposition principle and Fourier's theorem

21B Investigation: Wave Properties of Sound

Key Question:

How are the properties of waves used in the design of waves used in the design of musical instruments?

*Students read text section 21.3

AFTER Investigation 21B

21B Investigation Topics

� Make a simple musical instrument.

� Explain how a musical instrument controls frequency and wavelength.

� Produce complex sounds.

� Identify the frequencies of musical notes.

Chapter 21.3 Objectives and Vocabulary

� frequency spectrum

� sonogram

� cochlea

� Describe how the meaning of sound is related to frequency and time.

Learn how we hear sound.� cochlea

� rhythm

� musical scale,

� note

� octave

� beat

� consonance

� dissonance

� Learn how we hear sound.

� Describe the musical scale, consonance, dissonance and, beats in terms of sound waves.

� Learn about the role of harmonics in how instruments sound.