- published: 23 Jun 2015
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Weightlessness (or zero-g) is the condition that exists for an object or person when they experience little or no acceleration except the acceleration that defines their inertial trajectory, or the trajectory of pure free-fall. The physical path of an inertial trajectory depends only on the direction and strength of the sum of the gravitational attractions outside of the inertial reference frame.
The definition and use of 'Weightlessness' is difficult. Weight means the force exerted by gravity, weightless means the absence of such forces and weightlessness formally means the condition of zero gravitational force. In common use, however, 'weightlessness' (often with quotation marks) has the meaning given in the preceding paragraph. Astronauts and cosmonauts in the International Space Station are said to experience 'weightlessness', even though, at an altitude of a few hundred km, their weight (the gravitational force acting on them) is only about 10% less than on earth. Their orbit has a large centripetal acceleration towards the earth and their weight is the centripetal force producing it. However, the space station has (almost) exactly the same acceleration towards the earth. Consequently, in the frame of the space station, an unsupported person appears to have no acceleration and so his relative motion in this frame is the same as that of a person without weight in a spacecraft that is not accelerating. Hence the name 'weightlessness'.
David James Archuleta (born December 28, 1990) is an American pop singer-songwriter. At ten years old he won the children's division of the Utah Talent Competition leading to other television singing appearances. When he was twelve years old, Archuleta became the Junior Vocal Champion on Star Search 2. In 2007, at sixteen years old, he became one of the youngest contestants on the seventh season of American Idol. In May 2008 he finished as the runner-up, receiving 44 percent of over 97 million votes.
In August 2008 Archuleta released "Crush," the first single from his self-titled debut album. The album, released three months later, debuted at number two on the Billboard 200 chart; it has sold over 750,000 copies in the U.S., and over 900,000 worldwide. In October 2010 he released a third album, The Other Side of Down featuring lead single "Something 'Bout Love". In 2011, Archuleta announced he is taking a two-year hiatus to be a missionary of The Church of Jesus Christ of Latter-day Saints. As of February 2012, Archuleta has sold 1,108,000 albums and 3,327,000 tracks in the United States.