  We discuss the work-kinetic energy theorem and the mechanical energy
conservation theorem in the context of general physics courses. The motivation
is the fact that all modern texts on introductory mechanics show the same
conceptually dangerous statement that besides obliterating the concept of
mechanical work, diminishing the importance of the work-kinetic energy theorem,
leads to erroneous applications of the energy conservation theorem and at the
same eliminates its relationship with the principle of the conservation of the
mechanical momentum.
