velocities
81star cluster — Astron. a number of stars of common origin held together as a group by gravitational attraction. Cf. globular cluster, open cluster, stellar association. * * * ▪ astronomy Introduction either of two general types of stellar assemblages held… …
82Earth 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… …
83Artillery — For other uses of the term, see Artillery (disambiguation). Warfare Military history Eras Prehistoric Ancient …
84Earthquake — For other uses, see Earthquake (disambiguation). Global earthquake epicenters, 1963–1998 …
85Edwin Hubble — Infobox Scientist name = Edwin Hubble| birth date = birth date|1889|11|20|mf=y birth place = Marshfield, Missouri, U.S. residence = U.S. nationality = American death date = death date and age|1953|9|28|1889|11|20|mf=y death place = San Marino,… …
86Group velocity — [ Frequency dispersion in bichromatic groups of gravity waves on the surface of deep water. The red dot moves with the phase velocity, and the green dots propagate with the group velocity. In this deep water case, the phase velocity is twice the… …
87Open cluster — Galactic cluster redirects here. See also galaxy groups and clusters NGC 265, an open star cluster in the Small Magellanic Cloud An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and… …
88Supernova — This article is about the astronomical event. For other uses, see Supernova (disambiguation). Multiwavelength X ray, infrared, and optical compilation image of Kepler s supernova remnant, SN 1604. A supernova is a stellar explosion that is more… …
89Spacecraft propulsion — A remote camera captures a close up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to accelerate spacecraft and artificial… …
90Velocity — In physics, velocity is defined as the rate of change of position. It is a vector physical quantity; both speed and direction are required to define it. In the SI (metric) system, it is measured in meters per second: (m/s) or ms 1. The scalar… …
