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Wave PhysicsPHYS 2023
Tim Freegarde
07 Energy & power2020-21
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Coming up in Wave Physics...
• local and macroscopic definitions of a wave
• transverse waves on a string: • wave equation
• travelling wave solutions
• other wave systems: • electromagnetic waves in coaxial
cables
• shallow-water gravity waves
• sinusoidal waveforms, dispersion & standing waves
• this lecture:
• complex exponential waveforms
• energy and power
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Velocities of waves on a string
xx
• phase velocity of wave
• group velocity of wave
• velocity of transverse water motion
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Energy of waves on a string
xx
h(x)
δx
v
δy
• kinetic:
• potential:
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Energy density of waves on a taut string
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Energy density of waves on a taut string
MAX K.E. MAX P.E.
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Velocities of waves in shallow water
xx
• phase velocity of wave
• group velocity of wave
• velocity of transverse water motion
• velocity of longitudinal water motion
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Energy density of shallow water waves
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Energy density of shallow water waves
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Power of travelling waves
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13
Sumatra-Andaman earthquake 2004
• magnitude 9.15; 275,000 perished
Tsunami Inundation Mapping EffortsNOAA/PMEL - UW/JISAO
• 1200 km along India/Burma plate subduction zone
• slip of 15 m sideways, several metres vertically
• formed ridges 1.5 km high, trench kms wide
26 Dec 2004
• 30 km3 water displaced
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Sumatra-Andaman earthquake 2004
• magnitude 9.15; 275,000 perished
NOAA
• 1200 km along India/Burma plate subduction zone
• slip of 15 m sideways, several metres vertically
• formed ridges 1.5 km high, trench kms wide
• 30 km3 water displaced
• ocean waves ~ 60 cm
• 25 m high near shore
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Wave Physics
WAVE EQUATIONS &
SINUSOIDAL SOLUTIONS
wave equations, derivations and solution
sinusoidal wave motions
complex wave functions
WAVE PROPAGATION
Huygens’ model of wave propagation
interference
general wave phenomena
Fraunhofer diffraction
longitudinal waves
BEHAVIOUR AT
INTERFACES
continuity conditions
boundary conditions
SUPERPOSITIONSlinearity and superpositions
Fourier series and transforms
FURTHER TOPICSwaves from moving sources
operators for waves and oscillations
waves in three dimensions
http://www.avcanada.ca/albums/displayimage.php?album=topn&cat=3&pos=7
further phenomena and implications
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Wave PhysicsPHYS 2023
Tim Freegarde
