rb608 wrote:
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.

Indeed, I think you are correct. Seems I made another mistake copying
this stuff over, and I am still having trouble with the mathematical
model. I will have to check the originals and see if I made the same
mistake there. otherwise somebody would have picked up on it.
Or maybe they just read the theory and ignored the faulty equations?



(Frt - Flt) = Fi * Fa

= (0,01kgm/s² - Flt) = 0,03kg * 1m/s²


I am going to try and graph it with the data I have.

Thanks a lot for that, it seems to be correct, and agrees with some
other actual data I have. I am still not entirely sure it is correct,
but it seems to make sense.

My apologies for being somewhat short with you, I am rather inured to
some things by now, and they colour bo9th my judgement and my reactions.

TL
MC