Chapter 11 Wave Motion

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Chapter 11 Wave Motion

• WAVE The propagation of a disturbance through a
  medium without any net displacement of the medium

WAVE A self-sustaining disturbance of a medium
that propagates from one region to another,
carrying energy and momentum
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Chapter 11 Wave Motion

• The disturbance advances not the material medium

Waves are generated by an object in simple
harmonic motion
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Chapter 11 Wave Motion

• Two basic types of mechanical waves

Longitudinal and Transverse
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Chapter 11 Wave Motion

• LONGITUDINAL Wave
• A wave in which the particles of the medium
  oscillate in simple harmonic motion parallel to
  the direction of the wave propagation.

Longitudinal waves are a combination of both
COMPRESSION (squeezing) and RAREFACTION
(elongation)
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Fig 11.18, p. 384
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Chapter 11 Wave Motion

• TRANSVERSE Wave
• A wave in which the particles of the medium
  execute simple harmonic motion in a direction
  perpendicular to its direction of propagation.

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Fig 11.2, p. 372
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Fig 11.3, p. 372
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Chapter 11 Wave Motion

• Characteristics of a transverse wave

DISPLACEMENT, y, of a particle in a wave is the
displacement of that particle from its
equilibrium position and is measured by the
vertical distance, y . (in meters)
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Chapter 11 Wave Motion

• Characteristics of a transverse wave

AMPLITUDE, A, is the maximum value of the
displacement. (in meters)
WAVELENGTH, ?, is the distance, in the direction
of propagation, in which the wave repeats itself.
(in meters)
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Chapter 11 Wave Motion

• Characteristics of a transverse wave

PERIOD, T, is the time it takes for one complete
wave to pass a particular point. (in seconds)
FREQUENCY, f, is the number of waves passing a
particular point per second. (in Hz, cycles/sec,
sec-1, or /sec)
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Chapter 11 Wave Motion

• SPEED OF PROPOGATION, OR VELOCITY

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Chapter 11 Wave Motion

• SPEED OF A TRANSVERSE WAVE ON A STRING

Depends upon Tension, T, of the string and mass
per unit length
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Chapter 11 Wave Motion

• Reflection of a wave at a boundary
• End of string not fixed rigidly
• Pulse is reflected with same speed and in same
  orientation.
• End of string fixed rigidly
• Pulse is reflected with same speed, but is
  inverted

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Fig 11.10, p. 377
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Fig 11.11, p. 377
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Fig 11.12, p. 378
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Chapter 11 Wave Motion

• Reflection and Transmission of a wave at the
  boundary of two different media
• Less dense to more dense
• Pulse slows down
• Wavelength of transmitted wave is less than
  wavelength of incident wave.

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Chapter 11 Wave Motion

• Reflection and Transmission of a wave at the
  boundary of two different media
• Less dense to more dense
• Pulse slows down
• Wavelength of transmitted wave is less than
  wavelength of incident wave.

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Chapter 11 Wave Motion

• More dense medium to a less dense medium
• transmitted wave moves faster than the incident
  wave
• has a longer wavelength.

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More dense
Less dense
Same tension different densities
Notice different pulse widths
Inverted reflection
Fig 11.13a, p. 378
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Less dense
More dense
Same side reflection
Notice different pulse widths
Fig 11.13b, p. 378
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Fig 11.39, p.398
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Fig 11.40, p.399
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Fig 11.41, p.399
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Open at one end.
The end of a pipe that is open has an anti-node
(max pressure)
Fig 11.44, p.403
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Open at both ends.
The end of a pipe that is open has an anti-node
(max pressure)
Fig 11.45, p.403
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Fig 11.46, p.404
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