mechanical engineering: see engineering.

mechanical advantage: see machine.

Louisiana State University and Agricultural and Mechanical College, mainly at Baton Rouge; land-grant and state supported; coeducational; chartered 1853, opened as a state seminary 1860 near Alexandria (with W. T. Sherman as president), moved 1869. It became a university in 1870 and merged with the Agricultural and Mechanical College in 1877. There are law and veterinary schools at Baton Rouge, the LSU Health Sciences Center is at New Orleans, and there is a second medical school at Shreveport. University research facilities include a nuclear science center, a center for aquaculture research, and museums of geoscience and natural science.

Florida Agricultural and Mechanical University, at Tallahassee; land-grant and state supported; coeducational; chartered and opened 1887; predominantly African American. It has divisions of arts and sciences, education, engineering, agriculture, nursing, pharmacy, architecture, business, journalism, and graduate studies.

Condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs: Products are reverting to reactants at the same rate as reactants are forming products. For practical purposes, the reaction under those conditions is completed. Expressed in terms of the law of mass action, the reaction rate to form products is equal to the reaction rate to re-form reactants. The ratio of the reaction rate constants (i.e., of the amounts of reactants and products, each raised to the proper power), defines the equilibrium constant. Changing the conditions of temperature or pressure changes the reaction's equilibrium; a high temperature or pressure may be used to “push” a reaction that at ordinary conditions makes little product. See also H.-L. Le Châtelier.

Learn more about equilibrium, chemical with a free trial on Britannica.com.

Condition in which the net force acting on a particle is zero. A body in equilibrium experiences no acceleration and, unless disturbed by an outside force, will remain in equilibrium indefinitely. A stable equilibrium is one in which small, externally induced displacements from that state produce forces that tend to oppose the displacement and return the body to equilibrium. An unstable equilibrium is one in which the least departures produce forces tending to increase the displacement. A brick lying on the floor is in stable equilibrium, while a ball bearing balanced on a knife-edge is in unstable equilibrium.

Learn more about equilibrium with a free trial on Britannica.com.

Branch of engineering concerned with the design, manufacture, installation, and operation of engines, machines, and manufacturing processes. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics. It is concerned with machine tools, motor vehicles, textile machinery, packaging machines, printing machinery, metalworking machines, welding, air conditioning, refrigerators, agricultural machinery, and many other machines and processes essential to an industrial economy.

Learn more about mechanical engineering with a free trial on Britannica.com.

Sum of a system's kinetic energy (KE) and potential energy (PE). Mechanical energy is constant in a system that experiences no dissipative forces such as friction or air resistance. For example, a swinging pendulum that experiences only gravitation has greatest KE and least PE at the lowest point on the path of its swing, where its speed is greatest and its height least. It has least KE and greatest PE at the extremities of its swing, where its speed is zero and its height is greatest. As it moves, energy is continuously passing back and forth between the two forms. Neglecting friction and air resistance, the pendulum's mechanical energy is constant.

Learn more about mechanical energy with a free trial on Britannica.com.

or mechanical efficiency

In mechanics, the measure of the effectiveness with which a system performs. It is stated as the ratio of a system's work output to its work input. The efficiency of a real system is always less than 1 because of friction between moving parts. A machine with an efficiency of 0.8 returns 80percnt of the work input as work output; the remaining 20percnt is used to overcome friction. In a theoretically frictionless, or ideal, machine, the work input and work output are equal, and the efficiency would be 1, or 100percnt.

Learn more about efficiency with a free trial on Britannica.com.

Force-amplifying effectiveness of a simple machine (lever, wedge, wheel and axle, pulley, or screw). The theoretical mechanical advantage of a system is the ratio of the force that performs the useful work to the force applied, assuming there is no friction in the system. In practice, the actual mechanical advantage will be less than the theoretical value by an amount determined by the amount of friction.

Learn more about mechanical advantage with a free trial on Britannica.com.