kinetic theory of gases

Theory based on a simple description of a gas, from which many properties of gases can be derived. Established primarily by James Clerk Maxwell and Ludwig Boltzmann, the theory is one of the most important concepts in modern science. The simplest kinetic model is based on the assumptions that (1) a gas is composed of a large number of identical molecules moving in random directions, separated by distances that are large compared to their size; (2) the molecules undergo perfectly elastic (no energy loss) collisions with each other and with the walls of the container; and (3) the transfer of kinetic energy between molecules is heat. This model describes a perfect gas but is a reasonable approximation to a real gas. Using the kinetic theory, scientists can relate the independent motion of molecules of gases to their pressure, volume, temperature, viscosity, and heat conductivity.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

kinetic sculpture

Sculpture in which movement (as of a motor-driven part or a changing electronic image) is a basic element. Actual movement became an important aspect of sculpture in the 20th century. Pioneers such as Naum Gabo, Marcel Duchamp, László Moholy-Nagy, and Alexander Calder produced movement by such means as water, mechanical devices, and air currents (as in Calder's mobiles). Neo-Dadaist works such as Jean Tinguely's self-destructing Homage to New York (1960) embody the concept of a sculpture that functions as both an object and an event—a “happening.”

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

kinetic energy

Form of energy that an object has by reason of its motion. The kind of motion may be translation (motion along a path from one place to another), rotation about an axis, vibration, or any combination of motions. The total kinetic energy of a body or system is equal to the sum of the kinetic energies resulting from each type of motion. The kinetic energy of an object depends on its mass and velocity. For instance, the amount of kinetic energy math.Kmath.E of an object in translational motion is equal to one-half the product of its mass math.m and the square of its velocity math.v, or math.Kmath.E = 12math.mmath.v², provided the speed is low relative to the speed of light. At higher speeds, relativity changes the relationship.