
 Escape Velocity Encyclopedia Article @ LaunchBase.net (Site not responding. Last check: ) 
  In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a bounded distance from the source. 
  The simplest way of deriving the formula for escape velocity is to use conservation of energy, thus: in order to escape, an object must have at least as much kinetic energy as the increase of potential energy required to move to infinite height. 
  For a body rotating about its axis the escape velocity with respect to the surface does depend on direction e.g., for the Earth the rotational velocity is 465 m/s to the east at the equator, and the escape velocity to the east, with respect to the Earth's surface, is ca. 
 www.launchbase.net /encyclopedia/Escape_velocity (1455 words) 
