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friction

(Encyclopedia)friction, resistance offered to the movement of one body past another body with which it is in contact. In certain situations friction is desired. Without friction the wheels of a locomotive could not...

interstellar matter

(Encyclopedia)interstellar matter, matter in a galaxy between the stars, known also as the interstellar medium. The interstellar gas, which constitutes about 99% of the interstellar matter, consists mostly of hyd...

wasp

(Encyclopedia)wasp, name applied to many winged insects of the order Hymenoptera, which also includes ants and bees. Most wasps are carnivorous, feeding on insects, grubs, or spiders. They have biting mouthparts, a...

bivalve

(Encyclopedia)CE5 Internal anatomy of a clam, Anodonta, representative mollusk of the class Pelecypoda (the bivalves) bivalve, aquatic mollusk of the class Pelecypoda (“hatchet-foot”) or Bivalvia, with a la...

solar system

(Encyclopedia)CE5 Solar system CE5 solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the ...

camera

(Encyclopedia)CE5 Image formed by a camera camera, lightproof box or container, usually fitted with a lens, which gathers incoming light and concentrates it so that it can be directed toward the film (in an opt...

low-temperature physics

(Encyclopedia)low-temperature physics, science concerned with the production and maintenance of temperatures much below normal, down to almost absolute zero, and with various phenomena that occur only at such tempe...

metamorphism

(Encyclopedia)metamorphism, in geology, process of change in the structure, texture, or composition of rocks caused by agents of heat, deforming pressure, shearing stress, hot, chemically active fluids, or a combin...

molecular weight

(Encyclopedia)molecular weight, weight of a molecule of a substance expressed in atomic mass units (amu). The molecular weight may be calculated from the molecular formula of the substance; it is the sum of the ato...

impressionism, in painting

(Encyclopedia)impressionism, in painting, late-19th-century French school that was generally characterized by the attempt to depict transitory visual impressions, often painted directly from nature, and by the use ...