Statics
Statics is the branch of
physics concerned with the analysis of loads (
force,
moment,
torque) on a
physical systems in
static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at rest under the action of external forces of equilibrium. When in static equilibrium, the system is either at rest, or moving at constant velocity through its
center of mass.
By
Newton's second law, this situation implies that the net force and net
torque (also known as moment) on every body in the system is zero, meaning that for every force bearing upon a member, there must be an equal and opposite force. From this constraint, such quantities as
stress or
pressure can be derived. The net forces equalling zero is known as the
first condition for equilibrium, and the net torque equalling zero is known as the
second condition for equilibrium. See
statically determinate.
Statics is thoroughly used in the analysis of structures, for instance in
architectural and
structural engineering.
Strength of materials is a related field of mechanics that relies heavily on the application of static equilibrium.
Hydrostatics, also known as
fluid statics, is the study of fluids at rest. This analyzes systems in static equilibrium which involve forces due to mechanical fluids. The characteristic of any fluid at rest is when a force is exerted on any particle of the fluid is the same in any direction. If the force is unequal the fluid will move in the direction of the resulting force. This concept was first formulated in a slightly extended form by the
French mathematician and
philosopher Blaise Pascal in
1647 and would be later known as
Pascal's Law. This law has many important applications in
hydraulics. Galileo, also was a major father of hydrostatics.
In
economics, "static" analysis has substantially the same meaning as in physics. Since the time of
Paul Samuelson's
Foundations of Economic Analysis (1947), the focus has been on "
comparative statics", i.e., the comparison of one
static equilibrium to another, with little or no discussion of the process of going between them – except to note the
exogenous changes that caused the movement.
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Solid mechanics*
Free online test of statics conceptual knowledge*
Statics for Robotics*
Free online "Structural elements" text with summary chapter on statics
