gravity direction
81Black hole — For other uses, see Black hole (disambiguation). Simulated view of a black hole (center) in front of the Large Magellanic Cloud. Note the gravitat …
82Escape velocity — In physics, escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy, as calculated by the equation,:U g = frac{ Gm 1m 2}{r}.It is commonly described as the speed needed to …
83Unicycle — A unicycle is a human powered, single track vehicle with one wheel. Unicycles resemble bicycles, but are less complex. A Torker unicycle Contents 1 History …
84Spin (flight) — In aviation, a spin is an aggravated stall resulting in rotation about the center of gravity wherein the aircraft follows a downward corkscrew path. Spins can be entered unintentionally or intentionally, from any flight attitude and from… …
85Roller coaster elements — Contents 1 Basic elements 1.1 Brake run 1.2 Buzz bars 1.3 …
86spaceflight — /spays fluyt /, n. the flying of manned or unmanned spacecraft into or in outer space. Also, space flight. [1945 50; SPACE + FLIGHT1] * * * Introduction flight beyond Earth s atmosphere. This article deals with the basic concepts associated with …
87Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… …
88environmental works — ▪ civil engineering Introduction infrastructure that provides cities and towns with water supply, waste disposal, and pollution control services. They include extensive networks of reservoirs, pipelines, treatment systems, pumping stations …
89Friction — For other uses, see Friction (disambiguation). Classical mechanics …
90Orbital mechanics — A satellite orbiting the earth has a tangential velocity and an inward acceleration. Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other… …
