What makes Snap Casts (Interesting)

[gordonjudd]

If you are hit by a car, are you knocked over by a force or it’s momentum?

Vince,
I am sure from the analysis you did with colliding pool balls in your dynamics class you know (or should know) that you are knocked over by a change in the cars momentum to a change in your momentum.

Again change in momentum is the operative word in collision problems.

Gordy

[VGB]

Gordy

Perhaps you could elaborate on what this means?

Change that to "changes in the fly leg momentum" and I will agree with you.

If you mean the moving mass of the fly leg setting the loop into motion then I agree with you, both the loop and the fly leg undergo a change of momentum.

Vince

[VGB]

Gordy

I am sure from the analysis you did in colliding pool balls in your dynamics class you know (or should know) that you are knocked over by a change in the momentum of the car to a change in your momentum.

Again change in momentum is the operative word in collision problems.

Good, another thing we agree on.

Vince

[gordonjudd]

If you mean the moving mass of the fly leg setting the loop into motion If you mean the moving mass of the fly leg setting the loop into motion then I agree with you.

Vince,
If that is how you see loop formation then we still are not on the same page.

I still do not believe you can push a string when it undergoes compression. Thus I don't think the moving mass of the line is responsible for creating the loop and setting it in motion.

Rather the loop is formed because one end of the moving line is tethered and thus a loop is formed to match those boundary conditions.

Again you could try to launch a length of line such that its forward end is detached from the rod and see what happens. I don't think a loop will be formed, and thus your limp maxi-javelin will not go very far.

Gordy

[Paul Arden]

Have you guys ever seen this loop? It’s not very common but it’s not that uncommon. I’ve noticed it now maybe 30 or 40 times. Mike H pointed it out to me, and since then I’ve started to see it more than I’d like

Anyway the point is this: this loop unrolls perfectly. The flyleg runs around a tight circle and then around the loop.

I would be interested to know how this phenomenon fits with the respective camps here.

Thanks, Paul

[VGB]

Gordy

It would help reach agreement if you read my posts. Nobody is saying you can push string, except maybe people with bead chain fountains.

From yesterday:

http://www.sexyloops.co.uk/theboard/vie ... 337#p43337

Gordy, I agree with you but nobody is saying that you can push a string. All of the moving mass has momentum though. This is a good example:

https://vimeo.com/76220542

Vince

Vince

[Paul Arden]

Nice video link Vince.

[VGB]

Bernd posted it originally Paul, there’s lots going on in it. I haven’t reproduced your cast but I can get the fully round loop with the fly leading. I just need to invent a name and a purpose for it and I will be a famous caster as well.

Regards


Vince

[Dirk le Roux]

Hi Vince

You should film that cast sometime - I would be very interested to practically see what you explain there.

Regards,
Dirk

[VGB]

Hi Dirk

I’ve never been able to get a good enough contrast to pick up fly line on video but I may be able to do it with the MPR when I get back from Switzerland. It’s fairly easy to do, just a pure translation with little or no rotation.

Regards

Vince