The unsteady flow of an incompressible viscous fluid over a plane wall in the presence of a body force is considered. Three illustrative examples are given. In the first case, it is assumed that the body force is constant, in the second case the body force depends on time in the form of a positive pourer of time and in the third case the body force varies sinusoidally in time. In the case of the constant force the displacement and the momentum thickness grow as the square root of lime as in the case of the flow due to a flat plate suddenly set in motion. It is shown that there are similarities between the Slows considered In this paper and the Stoke's first and second problems.