Proper velocity by Hermann Minkowski's flat-space metric equation . Here a reference map frame of yardsticks and synchronized clocks define map position x and map time "t" respectively, and the "d" preceding a coordinate means infinitesimal change. A bit of manipulation allows one to show that proper velocity where as usual coordinate velocity . Thus finite "w" ensures that "v" is less than lightspeed "c". By grouping "γ" with v in the expression for relativistic momentum p, proper velocity also extends the Newtonian form of momentum as mass times velocity to high speeds without a need for relativistic mass. The proper velocity
This Is What Rock n' Roll Looks Like depth about the genre mix in "This Is What Rock n' Roll Looks Like": Although the song's title references the physical appearance of what rock and roll looks like, Porcelain Black revealed in an interview with AOL's "NoiceCreep" that rock and roll is not dependent on the physical appearance of someone. She stated: "This Is What Rock n' Roll Looks Like" received generally mixed reviews by critics, most of whom were surprised with Porcelain Black's outgoing persona and the pop production by RedOne. Gerrick D. Kennedy of "Los Angeles Times" complimented the song's production by stating that it could have