The following distinction is made in most of the elementary texts I've
used:
Work of ALL forces (the net force) = change in kinetic energy
Work of all nonconservative forces = change in total energy
because effect of conservative forces is taken into account in the
potential energy terms. Some texts use W' for the work of
nonconservative forces.
I have always found these two W-E theorems equally useful.
One thing to remember is that the force YOU (or I) exert is
nonconservative.
--
Martha Takats
Department of Physics and Astronomy
Ursinus College
Collegeville, PA 19426