Mass in special relativity what causes these particles to be termed "massless." However, even massless particles have a relativistic mass, which varies with their observed energy in various frames of reference, The invariant mass is the ratio of four-momentum (the four-dimensional generalization of classical momentum) to four-velocity: and is also the ratio of four-acceleration to four-force when the rest mass is constant. The four-dimensional form of Newton's second law is: The relativistic expressions for "E" and "p" obey the relativistic energy–momentum relation: where the m is the rest mass, or the invariant mass for systems, and "E" is the total energy. The equation is
Velocity (newspaper) in Louisville, and gay life. Regular weekly features included "The Bar Hopper", in which a local tavern was profiled; "The Party Crasher", a photo-story from the weekend's parties; and "What I'm Into", a mini-profile of a local person. "Velocity" was discontinued during a round of budget cuts by Gannett. Velocity (newspaper) Velocity was a free, weekly newspaper published between December 3, 2003 and June 15, 2011, by "The Courier-Journal" of Louisville, Kentucky. The full-color tabloid was distributed at 1,800 locations in a 13-county area in Kentucky and Southern Indiana. "Velocity" was widely seen as an attempt by the "Courier-Journal" and