- #1
greypilgrim
- 517
- 36
Hi.
We tried to make some quantitative measurements with a Pasco ripple tank system, a video camera and software for video analysis. We generated circular waves and tracked the propagation of a crest, from which the software computed the phase velocity:
We used 5 Hz, 10 Hz and 20 Hz; unfortunately I'm not sure what the setting was for this particular measurement (they all look similar anyway).
The phase velocity seems to stabilize around a constant value (as the wave velocity should be according to linear wave theory) somewhere before 2.0 s, but why is it so much faster before that?
It seems that the ripple generator does more than just excite the waves by moving up and down, maybe it introduces a nonlinearity of some sort?
Or might this be a dispersive effect? Then again, why would there be dispersion if the frequency is constant?
We tried to make some quantitative measurements with a Pasco ripple tank system, a video camera and software for video analysis. We generated circular waves and tracked the propagation of a crest, from which the software computed the phase velocity:
We used 5 Hz, 10 Hz and 20 Hz; unfortunately I'm not sure what the setting was for this particular measurement (they all look similar anyway).
The phase velocity seems to stabilize around a constant value (as the wave velocity should be according to linear wave theory) somewhere before 2.0 s, but why is it so much faster before that?
It seems that the ripple generator does more than just excite the waves by moving up and down, maybe it introduces a nonlinearity of some sort?
Or might this be a dispersive effect? Then again, why would there be dispersion if the frequency is constant?