Is the cast itself a transverse wave?
Posted: Mon Jan 08, 2018 11:59 pm
Hi Gordy,
Yes, I do understand that there is a classical definition of a transverse wave and that what you call the fly wave does not honour that definition. My argument seems to be that the definition itself breaks down when the transverse wave encounters the end of the medium through which it's travelling. The definition of a transverse wave seems to imply the medium has infinite length.
I'm saying that in a fly line, what would otherwise be called a transverse wave is reaching the end of the medium and is "breaking".
The difference here is that the end of the medium has been reached and the conditions for a transverse wave to exist are no longer satisfied (according to the definition in classical physics). If I were able to make that medium infinitely long (as approximated by the early part of the video) we'd still be talking about a transverse wave.
But then only Paul could deliver the fly ... and he'd still be wanting more backing.
Cheers,
Graeme
Yes, I do understand that there is a classical definition of a transverse wave and that what you call the fly wave does not honour that definition. My argument seems to be that the definition itself breaks down when the transverse wave encounters the end of the medium through which it's travelling. The definition of a transverse wave seems to imply the medium has infinite length.
I'm saying that in a fly line, what would otherwise be called a transverse wave is reaching the end of the medium and is "breaking".
So you're happy that the displacement of the waves is left and right? I have no problem at all with that because the wave is comprised of a string that has moved left and right. In other words, the medium has been displaced to the left and right. Do you agree with that?gordonjudd wrote: Thus if the fly end of the line was directly below the rod tip, then the propagation direction was down, and the displacement of the waves were left and right, i.e. transverse to the propagation direction.
This is where we are in disagreement and where I believe you are contradicting yourself. I agree that the displacement of the medium (line) is to the right, but the direction of propagation has not changed. It's still vertical. (I'll say this again: All I did was increase the amplitude and slow the speed of the rod tip. I did not change the direction of wave propagation. Please watch the video again and you'll see this happening.)At the end where you start making "fly waves" the propagation direction is to the right on the forward cast. The displacement of the line is also going to the right. Thus the displacement of the medium is aligned with the propagation direction, and could not be considered to be a transverse wave.
The difference here is that the end of the medium has been reached and the conditions for a transverse wave to exist are no longer satisfied (according to the definition in classical physics). If I were able to make that medium infinitely long (as approximated by the early part of the video) we'd still be talking about a transverse wave.
But then only Paul could deliver the fly ... and he'd still be wanting more backing.
Cheers,
Graeme