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Ch 15 Mechanical Waves © 2005 Pearson Education

15.1 Types of Mechanical Waves © 2005 Pearson Education

Mechanical wave is a disturbance that travels through some material or substance called the medium for wave. Mechanical wave is a disturbance that travels through some material or substance called the medium for wave. Transverse wave is the wave that the displacement of the medium are perpendicular or transverse to the direction of travel of the wave along the medium Transverse wave is the wave that the displacement of the medium are perpendicular or transverse to the direction of travel of the wave along the medium Longitudinal wave is the wave that the motions of particles is the same as the direction of wave. Longitudinal wave is the wave that the motions of particles is the same as the direction of wave. © 2005 Pearson Education

15.2 Periodic Waves © 2005 Pearson Education

periodic wave © 2005 Pearson Education

Example 15.1 Sound waves are longitudinal waves in air. The speed of sound depends on temperature at 20 ℃ it is 344m/s. What is wavelength of a sound wave in air at 20 ℃ if the frequency is 262 Hz? Sound waves are longitudinal waves in air. The speed of sound depends on temperature at 20 ℃ it is 344m/s. What is wavelength of a sound wave in air at 20 ℃ if the frequency is 262 Hz? ANS: ANS: © 2005 Pearson Education

15.3 Mathematical Description of a Wave sinusoidal wave moving in +x-direction © 2005 Pearson Education Phase

© 2005 Pearson Education

wave equation © 2005 Pearson Education

15.4 Speed of a Transverse Wave speed of a transverse wave on a string © 2005 Pearson Education Mass per unit length

© 2005 Pearson Education

15.5 Energy in Wave Motion © 2005 Pearson Education

Max Power average power, sinusoidal wave on a string © 2005 Pearson Education

inverse-square law for intensity © 2005 Pearson Education Average intensity

© 2005 Pearson Education

15.6 Wave Interference, Boundary Conditions, and Superposition © 2005 Pearson Education

Overlap of two wave pulses

principle of linear superposition © 2005 Pearson Education

standing wave on a string, fixed end at x = 0 © 2005 Pearson Education

15.7 Standing Waves of a String © 2005 Pearson Education

15.8 Normal Modes of a String © 2005 Pearson Education

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