Complete derivation of the momentum equation for the second grade fluid

In a recently accepted paper of R. A Van Gorder and K. Vajravelu [1] (Comments on “Series solution of hydromagnetic flow and heat transfer with Hall effect in a second grade fluid over a stretching sheet”) Central European Journal of Physics, DOI: 10.2478/s11534-009-0145-2 (online), the authors have made momentum equation for the second grade fluid very controversial. The aim of our thiscommunication is to give complete exact derivation of the momentum equation for second grade fluid and remedy this confusion.