....
We can reproduce Equation (667) by realizing that , where is the volume of a small co-moving volume element. Combining this expression with the definition of bulk modulus, , we obtain .
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... gives
Taking the finite compressibility of water into account, this equation generalizes to , where is the velocity of sound. However, the left-hand side of the general equation is negligible for gravity waves, whose propagation velocities are much less than .
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...quanta,
Plural of quantum: Latin neuter of quantus: how much.
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