In tranverse waves the motion of the disturbance is perpendicular to the direction of motion of the wave. Longitudinal waves propagate in the same direction as the motion of the disturbance of the medium. - PowerPoint PPT Presentation
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of motion of the wave. Longitudinal waves propagate in the same direction as the motion of the disturbance of the medium. The particles of surface waves move in a circular fashion, up and down, back and forth, as the wave passes through. 5. A wave pulse is a single disturbance, a continuous wave has a constant source for the disturbance which creates it. 20.The nodes be touched without disturbing the motion of the wave. 32.f = 0.1 Hz. T = 1/f = 1/(0.1/sec) = 10 sec.
Transcript
3. In tranverse waves the motion of the disturbance is perpendicular to the direction of motion of the wave.
Longitudinal waves propagate in the same direction as the motion of the disturbance of the medium.
The particles of surface waves move in a circular fashion, up and down, back and forth, as the wave passes through.
5. A wave pulse is a single disturbance, a continuous wave has a constant source for the disturbance which creates it.
20. The nodes be touched without disturbing the motion of the wave.
32. f = 0.1 Hz. T = 1/f = 1/(0.1/sec) = 10 sec.
33. = 10m. T = 2s f = 1/T = 1/2sec = 0.5/sec. v = fsec)(10m) = 5m/sec.
p. 34438,40,43,45
Wave VideosReflection off a sea wall: http://www.youtube.com/watch?v=PevRZAxDxZwBig wave at beach: http://www.weather.com/blog/weather/8_21326.htmlhttps://www.youtube.com/watch?v=QdoTdG_VNV4&feature=player_embedded#at=131Tacoma narrows bridge: http://video.search.yahoo.com/search/video;_ylt=A2KLqIGXaSdPEn0AIxT7w8QF?p=tacoma+narrows+bridge&b=21&tnr=20
Standing Waves in Musical Instruments Resonance: Stringed instruments, such as
the guitar, piano or violin, and horn and wind instruments such as the trumpet, oboe, flute and clarinet all form standing waves when a note is being played. The standing waves are of either the type that are
found on a string, or in an air column (open or closed).
These standing waves all occur at natural frequencies, also known as resonant frequencies, associated with the instrument.
Standing waves
• Two similar periodic waves traveling in opposite directions form a standing wave.
Standing Wave Characteristics
While a standing wave does not travel itself, it is comprised of two waves traveling in opposite directions. Harmonic: The series of frequencies where
standing waves recur (1f, 2f, 3f,…). Where the first frequency is called the first harmonic (1f), the second frequency is called the second harmonic (2f), and so on.
The first harmonic = the first fundamental frequency (n = 1).
Overtones: The harmonic frequency + 1.
Harmonics and Overtones of Standing Waves
www.cnx.rice.edu
Standing Wave Characteristics (cont.) The time for one wave to travel to
the barrier and back is:
T = 2L/v
For a string fixed at both ends with n antinodes:
fn = n(v/2L) n = 1, 2, 3, …
Each fn represents a natural or resonant frequency of the string.
This relationship can be rewritten for as follows.
= 2L/n
www.electron4.phys.utk.edu
www.cord.edu
Longitudinal Standing Waves Wind instruments, such as the flute, oboe,
clarinet, trumpet, etc. develop longitudinal standing waves. They are a column of air. May be open at one or both ends. Wave will reflect back regardless as to whether or not it
is open or close ended.
Longitudinal Standing Waves – Open Tube In an open tube instrument like the flute, the
harmonics follow the following relationship:
fn = n(v/2L) n = 1, 2, 3, …
www.cnx.rice.edu
Longitudinal Standing Wave Applet
Longitudinal Standing Waves –Tube Closed on One End
In a closed tube instrument like the clarinet or oboe, the harmonics follow the following relationship:
fn = n(v/4L) n = 1, 3, 5, …
www.cnx.rice.edu
How does a string make music?
•What does a string look like when vibrating?
How do I measure
AmplitudeWavelengthFrequencyPeriod
For each of these?
L = /2
V = nf/2L
Key Ideas Sound waves are generated by a vibrating object
such as the string on a violin, your vocal chords or the diaphragm of a loudspeaker.
Sound waves can be transmitted through gases, liquids and solids.
If there is no medium, there is no sound. Sound is generated by the cyclical collisions of
atoms and molecules. Condensation and rarefaction denote portions of
the wave that are of slightly higher and lower pressure, respectively.
Key Ideas Sound waves travel at different speeds in
different mediums. They speed up when going from air to a liquid to a
solid. Pure tone is sound of a single frequency. Pitch and loudness are characteristics of sound
that represent its frequency and amplitude, respectively.
When two sound waves overlap slightly due to mildly different frequencies, they generate a beat.
Harmonics occur at multiples of the natural frequency.
Sound Waves
How is Sound Transmitted? Sound is created by
the cyclical collisions of atoms and molecules such that it is transmitted through the bulk matter.
www.library.thinkquest.org
Sound Wave Characteristics Condensation or Compression: Region of the
wave where air pressure is slightly higher. Rarefaction: Region of the air wave where the
pressure is slightly lower. Pure Tone: A sound wave with a single frequency. Pitch: An objective property of sound associated with
frequency. Pitch High frequency = high pitch. Low frequency = low pitch.
Loudness: The attribute of sound that is associated with the amplitude of the wave.
Beat: When two sound waves overlap with a slightly different frequency. Beats
Speed of Sound Speed of sound depends on the medium through which it
travels.
kT
m
Where:
k = Boltzman’s constant (1.38 x 10-23 J/K)
= Cp/Cv (~5/3 for ideal monotonic gases)
T = Temperature (K)
m = Average mass of air (~28.9 amu)
Air Water Steel
Speed (m/s) 343 1482 5960
vrms =
Doppler Shift The change in sound frequency due
to the relative motion of either the source or the detector.
High Pitched Sound
Low Pitched Sound
www.physicsclassroom.com
The Doppler Effect
http://www.youtube.com/watch?v=imoxDcn2Sgo
http://www.youtube.com/watch?v=a3RfULw7aAY
http://www.youtube.com/watch?v=19_727LxYDw
Doppler This demo shows the Doppler effect in action Doppler
Waves: Take 2
Mr. Davis
Review: Key characteristics of waves
Period (if axis is time)
Amplitude: The height of the wave from node to antinode (transverse waves), or the pressure in a compressive wave. Measured in units describing the wave
Frequency: The rate of occurrence of the wave (in Hertz or cycles / second)
Wavelength: The distance traversed by a full cycle of the wave Node: The “zero point” of the waveAntinode: The extreme point of the wave (max or min amplitude)Period: The time between successive waves
The frequency
f = 1/T
where T is the period.
All of these terms are required for the Regents
What happens when two waves collide?
They pass through each other without changing and keep on going.(Have you ever crossed the beams of two flashlights to see what would happen?)
