Statics

Statics is the branch of mechanics concerned with the analysis of loads (force, torque/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 rest. When in static equilibrium, the system is either at rest, or its center of mass moves at constant velocity.

By Newton's second law, this situation implies that the net force and net torque (also known as moment of force) 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 that the force exerted on any particle of the fluid is the same in every 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. Archimedes, Abū Rayhān al-Bīrūnī, Al-KhaziniMariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in Harv|Morelon|Rashed|1996|pp=614-642: quote|"Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic apporach so that two trends - statics and dynamics - turned out to be inter-related withina single science, mechanics. The combination of the dynamic apporach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics. [...] Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science."] and Galileo Galilei were also major figures in the development 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.

In exploration geophysics, "statics" is used as a short form for "static correction", referring to bulk time shifts of a reflection seismogram to correct for the variations in elevation and velocity of the seismic pulse through the weathered and unconsolidated upper layers.

Other fundamental engineering topics

* Analysis of resistive circuits
* Dynamics
** Thermodynamics
** Fluid dynamics
* Engineering economics
* Heat transfer
* Materials science
** Strength of materials

See also

* Solid mechanics
* Graphic statics
** Funicular polygon
** Cremona diagram
*

References

External links

* [http://engineering-education.com/CATS/intro.htm Online test of statics conceptual knowledge(meant for teachers)]
* [http://www.cmu.edu/oli/courses/enter_statics.html Online interactive statics course] Open access.
* [http://www.societyofrobots.com/mechanics_statics.shtml Statics for Robotics]
* [http://instruct1.cit.cornell.edu/courses/arch264/text/index.html Free online "Structural elements" text with summary chapter on statics]
* [http://mark4561.freehostingnow.com/tutorials/Engineering_Tutorials.html Free Online Civil Engineering Tutorials: Statics]