Physics with Trig I

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Physics with Trig I
Revised 7/27/04
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Where weve been

• Newtons Laws of Motion
• Work Energy
• Conservation of Momentum
• Torque Angular Acceleration
• Solids Fluids
• The Ideal Gas Law
• Thermal Physics
• Waves

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Ch 14 Introduction
Sound waves are compressional waves by nature.
The medium is usually thought of as air but can
be any fluid or solid. In a solid, the waves can
also be transverse.
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Where were going
Ch 14 Sound (14.1) Producing a Sound Wave (14.2)
Characteristics of Sound Waves (14.3) The Speed
of Sound (14.4) Energy Intensity of Sound Waves
(14.6) The Doppler Effect (14.7) Interference of
Sound Waves (14.8) Standing Waves (14.9) Forced
Vibrations Resonance (14.10) Standing Waves in
Air Column
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(14.1) Producing a Sound Wave
The Loud Speaker Pushes and Pulls air molecules
to produce a Longitudinal Wave.
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(14.2) Characteristics of Sound Waves
Wavelength (?) Or Period (T)
Amplitude (A)
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(14.3) The Speed of Sound
The Speed of Sound in Various Media Table 14.1,
page 429. Notice velocity is affected
by temperature
In oC
velocity _at_ 0 oC
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(14.3) The Speed of Sound, contd

• ? bulk modulus
• ? ? mass density

For Liquid
For solids
Y ? Youngs Modulus
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(14.4) Energy Intensity of Sound Waves
Intensity ?
Decibel Ratio of two quantities. Here, two sound
levels.
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(14.4) Energy Intensity of Sound Waves, contd
o
But for sound measurements, the reference is
always the threshold of hearing
See Table 14.2, page 432 Problem 14.10
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(14.6) The Doppler Effect
Explanation Example 1 Example
2 Demonstration Website
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(14.7) Interference of Sound Waves
Constructive vs. Destructive Interference Demonst
ration of interference using loud speakers.
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Interference
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(14.8) Standing Waves
See Figure 14.18, page 443.
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(14.9) Forced Vibrations Resonance
Forced Vibrations A child in a
swing Resonance A bodies natural frequency of
vibration
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(14.10) Standing Waves in Air Column
See Figure 14.22, page 446 Example 14.11, page
448
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The End