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Old November 10th, 2008, 07:22 PM posted to rec.outdoors.fishing.fly
rb608
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Posts: 681
Default 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/sē * 0.3 = Flt / 0.01kgm/sē

30g * 1msē = 0,03kgm/sē

* 0,3 = 0.09 kgm/sē

Note that between the first and second equations, you simply discarded
the kg.m/sē 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/sē on the left.