Purpose and Emphasis. Mechanics not only is the oldest branch of physics
but was and still is the basis for all of theoretical physics. Quantum
mechanics can hardly be understood, perhaps cannot even be formulated,
without a good kno- edge of general mechanics. Field theories such as
electrodynamics borrow their formal framework and many of their building
principles from mechanics. In short, throughout the many modern
developments of physics where one frequently turns back to the
principles of classical mechanics its model character is felt. For this
reason it is not surprising that the presentation of mechanics re?ects
to some - tent the development of modern physics and that today this
classical branch of theoretical physics is taught rather differently
than at the time of Arnold S- merfeld, in the 1920s, or even in the
1950s, when more emphasis was put on the
theoryandtheapplicationsofpartial-differentialequations. Today,
symmetriesand invariance principles, the structure of the space-time
continuum, and the geom- rical structure of mechanics play an important
role. The beginner should realize that mechanics is not primarily the
art of describing block-and-tackles, collisions of billiard balls,
constrained motions of the cylinder in a washing machine, or - cycle
riding.