Group Velocity
The velocity at which the overall envelope shape of a wave packet travels through space, representing energy transport speed.
Governing formula
v_g = dω / dk
SI unit
m/s
In depth
In dispersive media, group velocity $v_g$ differs from individual wave crest speed (phase velocity $v_p$). Signal information travels at group velocity.
Examples in the real world
Deep ocean wave packets where individual ripples move through the packet faster than the overall wave group advances.