- A novel method is presented to solve the equations of motion for a large class of constrained and unconstrained dynamical systems. Given an analytic expression for the system mass matrix, quasivelocity equations of motion are derived in a manner that generates equations analogus to the dynamics/kinematics partitioning in Eulerian rigid body dynamics. ThiS separation is accomplished by introducing a new quasivelocity vector which yields a dynamical system with an identity mass matrix. The problem of inverting a complex mass matrix is replaced by the problem of solving two first-order differential equations for the mass matrix eigenfactors. Dynamic constraint equations are incorporated directly into the new differential equation, forgoing any need to solve the algebraic constraint equations simultaneously with the differential equations of motion.