Problem 9.22 from Griffiths:(adsbygoogle = window.adsbygoogle || []).push({});

Show that in deep water (where the depth is greater than the wavelength) the wave velocity is twice that of the group velocity. where Vw = w/k and Vg = dw/dk

where w is the angular frequency, and k is the wave number.

I'm really not certain how to proceed. Can someone give me a hint?

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# Homework Help: Wave vs. Group Velocity

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