Ok so we have different expressions for group velocity, g...
The most obvious being g = dw/dk
But then the text Im using says sinve w=vk we can write
g = v+k dv/dk
alongside other expressions, including k etc..
My question is - what is v in the equation above? I thought there were only two characteristic velocities of a wave packet which is the superposition of many different waves - the group and phase velocities.. What is the physical meaning of v here..