RJ Lawrence Tiu 4
Branches of physics
- is a model of the physics of forces acting upon bodies. It is often referred to as
"Newtonian mechanics" after Isaac Newton and his laws of motion. Mechanics is subdivided into statics, which
models objects at rest, kinematics, which models objects in motion, and
, which models objects
subjected to forces. The classical mechanics of continuous and deformable objects is continuum mechanics,
which can itself be broken down into solid mechanics and fluid mechanics according to the state of matter being
studied. The latter, the mechanics of liquids and gases, includes
aerodynamics, and other fields.
An important concept of mechanics is the identification of conserved energy and momentum, which lead to the
Lagrangian and Hamiltonian reformulations of Newton's laws. Liouville's theorem for statistical and
Hamiltonian mechanics is a classical nineteenth century result which describes the behavior of the phase space
distribution function. Liouville's theorem has a suggestive formulation, the Poisson bracket, which encodes
of classical mechanics, and has analogies with the commutator in quantum mechanics.
A relatively recent result of considerations concerning the dynamics of nonlinear systems is chaos theory, the
study of systems in which small changes in a variable may have large effects.
- studies the effects of changes in temperature, pressure, and volume on physical
systems at the
scale, and the transfer of energy as heat.
developed out of need to increase the
of early steam engines.
The starting point for most thermodynamic considerations are the laws of thermodynamics, which postulate that
energy can be exchanged between physical systems as heat or
They also postulate the existence of a
quantity named entropy, which can be defined for any system.
In thermodynamics, interactions between large
ensembles of objects are studied and categorized. Central to this are the concepts of
system is composed of particles, whose average motions define its properties, which in turn are related to one
another through equations of state. Properties can be combined to express internal energy and
, which are useful for determining conditions for equilibrium and spontaneous processes.