where the time derivate is with respect to the inertial frame and aE is the acceleration
of the body fixed frame expressed in the inertial frame, m is the mass of
the body which is constant and FE is the sum of all external forces applied to
the body expressed in the inertial frame. However, it would be convenient to express
the dynamics in the body fixed frame. By using the rotational matrix from
equation (3.5) a change of basis can be obtained and the expression becomes