Weightlessness

Weightlessness, or an absence of 'weight', is an absence of stress and strain resulting from externally applied mechanical contact-forces, typically normal forces from floors, seats, beds, scales, and the like. Counterintuitively, a uniform gravitational field does not by itself cause stress or strain, and a body in free fall in such an environment experiences no g-force acceleration and feels weightless. This is also termed "zero-g" where the term is more correctly understood as meaning "zero g-force."

When bodies are acted upon by non-gravitational forces, as in a centrifuge, a rotating space station, or within a space ship with rockets firing, a sensation of weight is produced, as the contact forces from the moving structure act to overcome the body's inertia. In such cases, a sensation of weight, in the sense of a state of stress can occur, even if the gravitational field was zero. In such cases, g-forces are felt, and bodies are not weightless.

When the gravitational field is non-uniform, a body in free fall suffers tidal effects and is not stress-free. Near a black hole, such tidal effects can be very strong. In the case of the Earth, the effects are minor, especially on objects of relatively small dimension (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity and it prevails in orbiting spacecraft.

Zero Gravity (disambiguation)

Zero gravity refers to weightlessness.

Zero gravity may also refer to:

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Sonic Riders: Zero Gravity

Sonic Riders: Zero Gravity, later released in Japan as Sonic Riders: Shooting Star Story (ソニックライダーズ シューティングスターストーリー, Sonikku Raidāzu: Shūtingu Sutā Sutōrī), is a hoverboard racing video game developed by Sonic Team and published by Sega. It is the fifth racing game in the Sonic the Hedgehog series, following Sonic Drift, Sonic Drift 2, Sonic R and its predecessor, Sonic Riders. A sequel titled Sonic Free Riders was released on November 4, 2010 exclusively for Kinect on Xbox 360.

Plot

The Story is split into two halves, the Heroes Story (Team Sonic), and Babylon Story (Babylon Rogues). Although the stories start separately, they overlap each other, telling the story as the main characters within that story see it. Following the format of Sonic Riders, Babylon Story also includes an epilogue that expands past the Heroes Story leading to the last course.

Sonic, Tails, and Knuckles are alerted to robots that are attacking a famous city of the future. They set out to retrieve a legendary artifact that has the ability to control gravity. Along the way they discover surprises, including the return of the Babylon Rogues, a group of avian thieves who are also after the artifacts. This sets off a war to decide who gets the artifact, leading them to settle their dispute by having an Extreme Gear competition.

NASA

Coordinates: 38°52′59″N 77°0′59″W / 38.88306°N 77.01639°W / 38.88306; -77.01639

The National Aeronautics and Space Administration (NASA) is the agency of the United States Federal Government responsible for the civilian space program as well as aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most US space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches.

NASA (Swedish band)

NASA is a Swedish synthpop band fronted by Patrik Henzel and Martin Thors. They debuted in 1983 with a song for a Swedish film. In 1985 they had a Swedish top ten hit "Paula". In the 1980s, the band had little success outside of Sweden. A planned US album was recorded, but then shelved by Columbia Records. They continued to have numerous hit singles in their home country of Sweden. They were basically defunct for most of the 1990s, but had a resurgence with the album "Remembering the Future" in 1999.

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NASA (disambiguation)

NASA is the National Aeronautics and Space Administration. NASA or Nasa may also refer to:

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