Force terms arising from radiation impinging on spatial and time inhomogeneities of a medium can frequently be represented by a simple partial differentiation operating on only the structural elements of the Lagrangian. These power and force density terms are energy and momentum sinks (or sources) of the raidation field. They accordingly occur as right-hand members in the usual divergence expressions for energy and momentum. The method of description is illustrated for acoustic radiation, for electromagnetic radiation in a material medium, and for electromagnetic radiation in a gravitational field. A coherent discussion of different kinds of radiation requires a reevaluation of the concept of wave momentum. The particlemomentum concept is implicit in the modified concept of wave momentum for "matter" waves. It then appears that the symmetry of the energy-momentum tensor only holds for electromagnetic radiation in free space and for matter waves associated with free and noninteracting particles.