physics 11 chapter #8 vibrations and waves mr. jean may 28 th, 2012
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Physics 11
Chapter #8 Vibrations and Waves
Mr. JeanMay 28th, 2012
The plan:
Video Clip of the dayVideo Clip of the day Science Fair PresentationsScience Fair Presentations Introduction to waves Introduction to waves Ways to transmit & transfer energyWays to transmit & transfer energy Wave interferenceWave interference
Science Fair:
CherCher Abby’s GroupAbby’s Group
In symbolic form
T 1foror
T1f
Example Question: A mass suspended from the end of a spring A mass suspended from the end of a spring
vibrates up and down 24 times in 36 vibrates up and down 24 times in 36 seconds. What is the frequency and period seconds. What is the frequency and period of the vibration? of the vibration?
Example Question: A mass suspended from the end of a spring A mass suspended from the end of a spring
vibrates up and down 24 times in 36 vibrates up and down 24 times in 36 seconds. What is the frequency and period seconds. What is the frequency and period of the vibration? of the vibration?
Wave Characteristics:
http://www.brightstorm.com/scienchttp://www.brightstorm.com/science/physics/vibration-and-waves/wave/physics/vibration-and-waves/wave-characteristics/e-characteristics/
3. WAVE MOTION
Energy is transported by particles or waves.
A wave is a disturbance transmitted through
a medium.
Exception: light does not require a medium.
4. WAVE SPEED
The average speed is defined asThe average speed is defined as
time
distancev
For a wave, if the distance traveled is a For a wave, if the distance traveled is a
wavelengthwavelength ( (), then the time to travel this ), then the time to travel this
distance is the distance is the periodperiod (T). Then (T). Then
Tv
fv oror
is true for all waves.
Note: v is dictated by the medium.
(must change medium to change v)
f is dictated by the source.
(must change the source to change f )
Demo - Complete Bell Wave MachineDemo - Complete Bell Wave Machine
fv
5. TRANSVERSE WAVES
Demonstration: Transverse WavesDemonstration: Transverse Waves
Examples: string musical instruments
ripples on water
electromagnetic waves
6. LONGITUDINAL WAVES
Video - Slinky Longitudinal WavesVideo - Slinky Longitudinal Waves
Parameters
Rarefactions are regions of low density.
Compressions (condensations) are regions of high density.
is the distance between successive rarefactions or successive compressions.
7. INTERFERENCE
Video - Superposition of WavesVideo - Superposition of Waves
SlideSlide - Interference - Interference
Constructive interference occurs when waves are in phase, that is when crests are superimposed and troughs are superimposed.
Destructive interference occurs when waves are out of phase, that is when crests are superimposed with troughs.
Interference is a characteristic of all waves.
Demonstrations with Audacity
Standing Waves
When two sets of waves of equal amplitude and wavelength pass through each other in opposite directions, it is possible to create an interference pattern that looks like a wave that is “standing still.” It is a changing interference pattern.
Demo - Rope and strobeDemo - Rope and strobe Demo - Mechanical overhead modelDemo - Mechanical overhead model
There is no vibration at a node. There is maximum vibration at an antinode. is twice the distance between successive
nodes or successive antinodes.
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