Unformatted text preview: he wave) that pass a given point in a unit time
interval
– The time interval is most commonly the second
– The frequency of the wave is the same as the
frequency of the simple harmonic motion of one
element of the medium When the time interval is the second, the units of
frequency are s1 = Hz
Hz is a hertz Wave Function, Another Form
• Since speed is distance divided by time, v= /T • The wave function can then be expressed as • This form shows the periodic nature of y in
both space and time Wave Equations
• We can also define the angular wave number (or
just wave number), k • The angular frequency can also be defined Wave Equations, cont
• The wave function can be expressed as
•
y = A sin (k x – t)
• The speed of the wave becomes v = ƒ
• If x
at t = 0, the wave function can be
generalized to
y = A sin (k x – t + )
where is called the phase constant Different descriptions
of the wave Transverse and Longitudinal Propagation v FT m/l
v S Energy in Waves in a String
• Waves transport energy when they propagate
through a medium
• We can model each element of a string as a
simple harmonic oscillator
– The oscillation will be in the ydirection
• Every element has the same total energy Energy in a string
• Each element can be considered to have a mass of m
• Its kinetic energy is
K = 1/2 ( m) vy2 • The mass m is also equal to
• K = 1/2 ( x and x) vy2 • As the length of the element of the string shrinks to zero, the
equation becomes a d...
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This document was uploaded on 02/21/2014 for the course CHEM 110A 110a at UCLA.
 Winter '13

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