Hauling, Rod-loading.

On Nov 10, 1:35*pm, "
wrote:
Whether the mathematical model is entirely accurate, I am no longer
sure. *I will have to check it again.

I believe the magnitude of the air resistance to be relatively
inconsequential to the casting mechanics (though on a windy day, it's
effect is undeniable afterward), so with your permission, I'll leave
it out for simplicity. That makes your equation to be:

Frt = Fi * Fa * Flt

It's my contention, however, the the force terms should be grouped,
and that the unbalanced force causing the line acceleration is
actually (Frt - Flt). This allows your model to fit into the F=ma
equation as:

(Frt - Flt) = Fi * Fa

I don't think that's a great deal different than you were describing
it verbally; but it *is* a great deal more accurate as a physics
equation.


The units issue I mentioned is manifest in this series of equations
from your post:

30g * 1m/s² * 0.3 = Flt / 0.01kgm/s²

30g * 1ms² = 0,03kgm/s²

* 0,3 = 0.09 kgm/s²

Note that between the first and second equations, you simply discarded
the kg.m/s² units in the demoninator, using only the same units that
go with the Flt force in the numerator. Had you retained those units
as you should have, the numerator and denominator units would cancel
and you'd have ended up with no units at all on the right side, but
g.m/s² on the left.

On Mon, 10 Nov 2008 13:37:52 -0800 (PST),
wrote:


If you go back to the fence post model for a moment. Lay a line on the
ground and tie one end to the top of the post. Slowly pull the line
taut. The first thing that happens is that the line lifts into the air
as a result of the tension on it.

It lifts into the air because, well, simply, the shortest distance
between two points is a straight line, and you started out by exerting
the force necessary for it to overcome gravity by tying one end to the
top of a post. Lay the end of the line on the top the post and see what
happens.

I'm not sure what all this is trying to demonstrate, but if you'll start
with the known, hauling increases line speed, and work back, you might
get there quicker. IIRC, in one of the rounds of ROFFian "Does hauling
load the rod," someone posted a link to a bunch of Greek-letter
gobbledygook, so the calcs have been done already...and I assume
accurately because the engineering weenies around here didn't go into
cardiac arrest - they may not know **** about the stock market, politics
or pussy, but I'll put some of these geeks around here up against a team
of Cal Tech AND MIT pasty-faced pimple-mashers any day of the week...

HTH,
R