6: Module 5 - Oscillations, Waves, and Sound
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- 6.1: Objective 5.a.
- Many types of motion involve repetition in which they repeat themselves over and over again. This is called periodic motion or oscillation, and it can be observed in a variety of objects such as grandfather clocks and musical instruments. These objects always contain a stable equilibrium position that the moved body will return to after some displacement. This section will focus on analyzing the oscillations of two simple systems to develop a foundation for the later section's study on waves.
- 6.2: Prelude to Sound
- Sound is an example of a mechanical wave, specifically, a pressure wave: Sound waves travel through the air and other media as oscillations of molecules. Normal human hearing encompasses an impressive range of frequencies from 20 Hz to 20 kHz. Sounds below 20 Hz are called infrasound, whereas those above 20 kHz are called ultrasound. Some animals, like bats, can hear sounds in the ultrasonic range.
- 6.3: Sound Waves
- Sound is a disturbance of matter (a pressure wave) that is transmitted from its source outward. Hearing is the perception of sound. Sound can be modeled in terms of pressure or in terms of displacement of molecules. The human ear is sensitive to frequencies between 20 Hz and 20 kHz.
- 6.4: Speed of Sound
- The speed of sound depends on the medium and the state of the medium. In a fluid, because the absence of shear forces, sound waves are longitudinal. A solid can support both longitudinal and transverse sound waves. The speed of sound is the same for all frequencies and wavelengths of sound in air.
- 6.5: Objective 5.b.
- In this chapter, we will study the physics of wave motion. We concentrate on mechanical waves, which are disturbances that move through a medium such as air or water. Like simple harmonic motion studied in the preceding chapter, the energy transferred through the medium is proportional to the amplitude squared. The concepts presented in this chapter will be the foundation for many interesting topics, from the transmission of information to the concepts of quantum mechanics.