Statics
Statics is the branch of
mechanics
that is concerned with the analysis of loads (
force and
torque, or
"moment") on
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 a constant velocity. When in static equilibrium, the system
is either at rest, or its
center of mass moves at constant velocity.
By
Newton's first law, this situation implies
that the net force and net torque (also known as moment of force) on every part
of the system is zero. From this constraint, such quantities as
stress or
pressure can be
derived. The net forces equaling zero is known as the
first condition for
equilibrium, and the net torque equaling zero is known as the
second
condition for equilibrium. See
statically determinate.