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Sitter, Willem de

(Encyclopedia)Sitter, Willem de vĭlˈəm də sĭtˈər [key], 1872–1934, Dutch astronomer and mathematician. He was professor from 1908 at the Univ. of Leiden and in 1919 became director of its observatory. His ...

special effects

(Encyclopedia)special effects, in motion pictures, cinematographic techniques that create illusions in the audience's minds as well as the illusions created using these techniques. Some common examples are the use ...

shock absorber

(Encyclopedia)shock absorber, device for reducing the effect of a sudden shock by the dissipation of the shock's energy. On an automobile, springs and shock absorbers are mounted between the wheels and the frame. W...

vibration

(Encyclopedia)vibration, in physics, commonly an oscillatory motion—a movement first in one direction and then back again in the opposite direction. It is exhibited, for example, by a swinging pendulum, by the pr...

animated cartoon

(Encyclopedia)animated cartoon: see Nontheatrical Film under motion pictures. ...

force

(Encyclopedia)force, commonly, a “push” or “pull,” more properly defined in physics as a quantity that changes the motion, size, or shape of a body. Force is a vector quantity, having both magnitude and dir...

celestial mechanics

(Encyclopedia)celestial mechanics, the study of the motions of astronomical bodies as they move under the influence of their mutual gravitation. Celestial mechanics analyzes the orbital motions of planets, dwarf pl...

Empedocles

(Encyclopedia)Empedocles ĕmpĕdˈəklēz [key], c.495–c.435 b.c., Greek philosopher, b. Acragas (present Agrigento), Sicily. Leader of the democratic faction in his native city, he was offered the crown, which h...

Burbank

(Encyclopedia)Burbank, city (2020 pop.107,337), Los Angeles co., S Calif.; inc. 1911. Tourism and the entertainment industry are central to its economy; several motio...

frequency

(Encyclopedia)frequency: see harmonic motion; wave. ...