Delta-v (physics) such as determining the change in momentum (impulse), where :formula_4, where formula_5 is momentum and m is mass. Delta-v (physics) Delta comes as the 4th letter in the greek alphabets which is spell as 'D' in the english alphabets . In general physics, delta-"v" is simply a change in velocity. The Greek uppercase letter delta is the standard mathematical symbol to represent change in some quantity. Depending on the situation, delta-"v" can be either a spatial vector (Δv) or scalar (Δ"v"). In either case it is equal to the acceleration (vector or scalar) integrated over time: If acceleration is constant,
Mass in special relativity derived form formula_44 is not valid because formula_45 in formula_46 is generally not a constant (see the section above on transverse and longitudinal mass). Even though Einstein initially used the expressions "longitudinal" and "transverse" mass in two papers (see previous section), in his first paper on formula_47 (1905) he treated "m" as what would now be called the "rest mass". Einstein never derived an equation for "relativistic mass", and in later years he expressed his dislike of the idea: Okun and followers reject the concept of relativistic mass. Also Arnold B. Arons has argued against teaching the concept of relativistic