As a rod is a spring, and spring tension may be equated to string
tension, one may use the same units. This also facilitates conversion
etc.

The basic premise is of course that every action provokes an equal and
opposite reaction ( Newton´s third law). This means that in the system
there is always equilibrium at any given point. The force on the rod
tip therefore must equal the tension in the line, except when hauling,
where the haul force primarily increases line tension.

This applies regardless of whether the system is moving or not. A
static equivalent would be attaching the line to a fence post, and
bending the rod against the tension of the line. The line tension is
directly proportional to the rod loading ( spring force). The force
on each end of the system is identical ( ignoring hysterysis* when
dynamically applied ) in equlibrium.


*hysteresis (hÄ*s'tÉ™rÄ“`sÄ*s), phenomenon in which the response of a
physical system to an external influence depends not only on the
present magnitude of that influence but also on the previous history
of the system. Expressed mathematically, the response to the external
influence is a doubled-valued function; one value applies when the
influence is increasing, the other applies when the influence is
decreasing. Magnetic hysteresis occurs when a permeable material like
soft iron is magnetized by being subjected to an external magnetic
field. The induced magnetization tends to lag behind the magnetizing
force. If a field is applied to an initially unmagnetized sample and
is then removed, the sample retains a residual magnetization (it has
become a permanent magnet). The graph of the magnetic induction B
versus the magnetic field H is called a hysteresis loop. The area of
the loop is proportional to the energy dissipated as heat when the
system goes through a cycle; this represents a considerable energy
loss in alternating-current machinery. Thermal hysteresis occurs when
the value of a given property of a body depends not only on the body's
temperature but also on whether the temperature is rising or falling.
An example is the dielectric constant versus temperature for certain
crystals. Another kind of hysteresis is a common feature of control or
cybernetic systems. A familiar example is a thermostat controlling a
source of heat and set at some temperature T0. When the room
temperature falls through T0 to some lower temperature T1, the heating
power is switched on. When the room temperature rises through T0 to
some higher temperature T2, the power is switched off. Thus, for
temperatures lower than T1, the heat is always on; for temperatures
higher than T2, the heat is always off; but for temperatures between
T1 and T2, the heat may be on or off (double-valued response),
depending on which of the two temperatures T1 and T2 occurred most
recently in the system's history. Unlike the previous examples, this
hysteresis effect is not naturally occurring; it is designed into the
control system to prevent the damage to the system that would arise
from switching on and off too frequently.

TL
MC