Effective mass (solid-state physics) from both sides gives where is the th element of , is the th element of , and are the th and th elements of , respectively, and is the total energy of the particle according to the Planck–Einstein relation. The index is contracted by the use of Einstein notation (there is an implicit summation over ). Since Newton's second law uses the inertial mass (not the gravitational mass), we can identify the inverse of this mass in the equation above as the tensor This tensor expresses the change in group velocity due to a change in crystal momentum. Its
This Is What Rock n' Roll Looks Like at number forty-four on the US "Billboard" Hot Dance Club Songs. A music video for "This Is What Rock n' Roll Looks Like", shot and directed by Sanaa Hamri, was released on March 27, 2011. The music video pays homage to Porcelain Black's high school experiences, where she was constantly teased by "snobby rich kids", but never gave in to the pressure of her peers around her. The video serves as a form of revenge for Porcelain Black against high school tormentors. "This Is What Rock n' Roll Looks Like" garnered mixed reviews from critics, most of whom were shocked