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Tutorial Lab only open 12-2 pm tomorrow
Tomorrow = last day to register your clicker and still get credit for past quizzes. Look at your clicker right now… is one of these your number?

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“What’s on the exam” handout
Exam starts tomorrow in Testing Center (HGB).
Anyone not know about the T.C.? See http://testing.byu.edu
.
a. T.C. opens tomorrow at 8 am.
Exam ends next Saturday a. Correction to syllabus: on Saturdays, the Testing
Center gives out last exam at 3 pm, closes at 4 pm.
Can bring handwritten 3x5 card (both sides)
I will give you all constants/conversion factors you need
Can use your own calculator (storing stuff in calc memory violates spirit if not letter of the law)
Time goal: 2 hours avg (took me 35 mins)

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“Adiabatic Cotton Burner”

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Skipping: Oscillations, Ch. 15
Today: Basic wave info
Next week: Detour to “Physics Phor Phynatics”, Dr.
Durfee’s book a. For Monday, S&J 16.3-16.6; PpP 2.1, 2.2. b. 2.4.1 & 2.4.2 also recommended (but not 2.3 or
2.4.3)
Wed = complex numbers. Quick survey via clickers: a. Do you know complex numbers fairly well?
A = “know fairly well”; B = “not” b. Have you seen: e ix = cosx + isinx ?
A = “have seen”; B = “not”

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Which of the following phenomena can NOT exhibit a combination of transverse and longitudinal waves?
a. sound waves in air b. surface water waves c. waves in the earth generated by an earthquake

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What do these functions look like?
a. f(x) = x 2 b. f(x) = (x – 1) 2
Quick writing: What would be an equation for a parabola that moves 1 m to the right every second?
What will this function look like at 0 s? at 1 s? at 2 s?
a. f(x) = (x – 5t) 2 b. What is its “velocity”?

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Nothing special about parabolas…
What does f(x) = cos(x – vt) look like at t = 0? at t = a little later?
Add in “amplitude”
Add in “phase”
What if you want wave to move right-to-left?
“Wave function”

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Definition: oscillating disturbance that transfers energy (but not mass).
Direction
Medium
Transverse vs Longitudinal
Examples… a. Water b. Earthquake (P & S) c. Sound d. Light e. Rubber tubing (demo) f. Slinky (demo)
Wikipedia: “S-wave”

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The handing out of the slinkies a. We only have 34 b. There are 46 students in the class

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http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html

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Web demo: Stokes’ “Traveling Sine Wave” http://stokes.byu.edu/sinewave_script_flash.html
Wavelength l a. m/wave
Period T
v = f l a. s/wave
Frequency ( f = 1/T ) a. waves/s
Speed v a. m/s

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AM1320 KFAN broadcasts the Utah Jazz games at a frequency of 1320 kHz. (Check out www.jazzfanz.com
 .) Radio waves travel at the speed of light, 3  10 8 m/s. (a) What is the wavelength of the AM1320 radio waves? (b)
What is the period?

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Let’s call it “s(x)” (because “f” is used for frequency)
What does s(x) represent?
a. For transverse waves… b. For longitudinal waves…
What does s  (x) represent?

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 2 s
 t
2

C
 2 s
 x
2
C
 v
2
Why is it called the wave equation?
a. Because traveling waves are solutions of the equation!
s

A cos(

) Any function that has
“x-vt” will work! …or “x+vt”
 s
 x
 
A sin( x
 vt )
 2 s
 x
2
 
A cos( x
 vt )

 s t
 
A sin( x
 vt )
 
Av sin( x
 vt )
 
 2 s
 t
2
 
Av cos( x
 vt )
 
 
Av
2 cos( x
 vt )

w
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What’s the difference between these: s
 cos( x

5 ) s
 cos(2( x

5 ))
General form of cosine wave: s

A cos( (

)
 
)
…sometimes written as: s

A cos( kx
 w 
)
 k = “wavevector”; w = “angular frequency” w = …