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
This Is What Rock n' Roll Looks Like their real names, Alaina Beaton and Dwayne Carter, Jr. respectively. After being introduced to Lil Wayne's manager, Derrick "EI" Lawrence, by producer RedOne, Porcelain Black stated that she met Lil Wayne in New York City when he heard "This Is What Rock n' Roll Looks Like", where he expressed an interest in adding his vocals to the song. The single cover for "This Is What Rock n' Roll Looks Like" was revealed on March 21, 2011, alongside a snippet of the song. "This Is What Rock n' Roll Looks Like" was released digitally through the United States iTunes Store on