WAVES, page 2



(6) - Wave classification, e.g. by period (ripple, swell, tsunami, tide), o r
depending on relation between wavelength and waterdepth:
deep water wave (depth=1/2 Ld ) intermediate wave(depth=1/20 L)d shallow water wave
________Ld___________...........................................................s.l......................................X = shoreline




make sketch
start seafloor here
X

deep water wave only depends on T:

wave length Ld (in meters) equals 1.56 T 2(wave period squared, in seconds)

So, a 10 second wave in deep water
will have wave length of ........m
intermediate waves

too complicated
(with hyperbolic tangents)
shallow water wave only depends on waterdepth (d):

C = (gd)1/2, o r
celerity = square root of g = "gravity"
(say 10 m.sec-2) x depth

so in 5 m depth, wave travels at ........................m/sec or .................km/hr and in 3 m, wave travels at ........................m/sec or .................km/hr

(7) - Wave Energy: E = 1/8 (rho) g H2 L ,

where (rho) = density (gramcm-3) or weight/volume, or mass.acceleration/volume, MLT-2/ L3 = ML-2T
a n d
g = "gravity" = 980 cm/sec2, say 10ms-2, of LT-2

NOTE 1: essentially, the first 3 terms in the above equation are constants
density of water is about 1 g.cm3, but what would be the energy of a wave in a quicksilver (mercury) ocean?....
g="gravity", only applies to Earth, and would be different elsewhere.
Thus, the formula reduces to E=kH2L


NOTE 2: read this as :" wave energy is directly proportional to the wavelength and to the square of the waveheight"
so that if one wave is three times as long as another, it will have 3 times as much energy,
b u t if one wave is three times as high as another, it will have 3 2, or 9 times as much energy


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