On Nov 10, 2:22*pm, rb608 wrote:
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


Having said this however, I'd clarify that in reality, the line
tension Flt and the force on the rod tip (parallel to the line) Frt
are the same force (in opposite directions), because it's the rod tip
that imparts that force to the line. One needs to examine exactly
where one wishes to consider the free-body diagram. Because we're
looking at how the line accelerates, we can leave the rod out of the
equation altogether. The unbalanced force imparted as line tension by
the rod tip F will cause the mass of the line m to accelerate at a
rate a. Because m is constant, more F causes faster a. It's not a
static model because a0. It's a lot simpler mathematically than it
is with a rod in your hands (well, my hands anyway.)