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quasar987

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## Main Question or Discussion Point

I'm having extreme difficulties finding understandable informations on the why and how on the topic of wave paquets, dispersion, phase and group velocity. My question is this.

The motion of waves of small wavelenght at the surface of water is governed by the surface tension. The phase velocity of such waves is givent by the expression v_p = ...

a) Show that the group velocity of a superposition of waves of comparable wavelenght is v_g = 3v_p/2. (I've done that, though I don't really understand why what I've done is true)

b) What is the implication of this result on the observation of the motion of such a superposition of waves at the surface of water?

My answer would be: we would observe that the modulation of amplitude of the waves move faster than the waves themselves.

Some clarification and any info whatesoever would be warmly welcomed. I can't believe how unlclearly the teacher has bombared us with this stuff!

The motion of waves of small wavelenght at the surface of water is governed by the surface tension. The phase velocity of such waves is givent by the expression v_p = ...

a) Show that the group velocity of a superposition of waves of comparable wavelenght is v_g = 3v_p/2. (I've done that, though I don't really understand why what I've done is true)

b) What is the implication of this result on the observation of the motion of such a superposition of waves at the surface of water?

My answer would be: we would observe that the modulation of amplitude of the waves move faster than the waves themselves.

Some clarification and any info whatesoever would be warmly welcomed. I can't believe how unlclearly the teacher has bombared us with this stuff!