An extended analytic approach is considered for optical Bloch equations in the two level atom interacting with laser light. The separation approach of coupled differential equations is always possible with a sequence of special transformation into the Riccati nonlinear differential equation. The conditions that permit an exact solutions of three coupled system are extracted in a natural manner. The case of sodium atom moving along the axis of a monochromatic wave is treated in some details including a discussion on the radiation pressure forces exerted by laser light in the transient regime.KEY WORDS: optical Bloch equations; light-atom interactions; coupled differential equations; transient regime; mechanical effects of light; dissipative and reactive forces.