accelerating force
61Ion thruster — An ion thruster is a form of electric propulsion used for spacecraft propulsion that creates thrust by accelerating ions. Ion thrusters are characterized by how they accelerate the ions, using either electrostatic or electromagnetic force.… …
62Frame of reference — A frame of reference in physics, may refer to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it, or it may refer to an observational reference frame tied to the state of… …
63Introduction to general relativity — General relativity (GR) is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by… …
64Coriolis effect — For the psychophysical perception effect, see Coriolis effect (perception). Classical mechanics Newton s Second Law …
65Russia — /rush euh/, n. 1. Also called Russian Empire. Russian, Rossiya. a former empire in E Europe and N and W Asia: overthrown by the Russian Revolution 1917. Cap.: St. Petersburg (1703 1917). 2. See Union of Soviet Socialist Republics. 3. See Russian… …
66Unemployment — World unemployment rates[1] as of January 2009[update] Unemployment (or …
67Apparent weight — An object s weight, henceforth called actual weight , is the downward force exerted upon it by a gravitational field. By contrast, an object s apparent weight is the (usually upward) force (the normal force , or reaction force ), typically… …
68Dark energy — Not to be confused with dark matter, dark fluid, or dark flow. Physical cosmology …
69Physical 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… …
70Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …
