phase velocity and wave propagation velocity

[morrobay]

1. The problem statement, all variables and given/known data
wavelength = 3m
frequency =25 cycles/sec
period T = 1/frequency = .04 sec/cycle
wave propagation velocity =75 m/s
wave number K = 2pi/wavelength= 2.09 radians/m
angular frequency w = 2pi/T = 157 radians/s
phase velocity Vp = w/k = 157/2.09 = 75meters/second

----------------------------------------------------------------x = 200 meters, t= 2.66 s

In the above propagation velocity = phase velocity.

What would vary here for phase velocity to be greater than propagation velocity ?
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1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution