In this study, forced vibration of a rotating disk is investigated. The disk is clamped at the inner and free at the outer circumferences. A time varying excitation force is applied to a spacefixed point on the disk surface perpendicularly. The presence of multiple excitation forces is also considered in the paper. These forces can be applied to any spacefixed point on the disk surface. The disk is modelled as a thin plate and the Galerkin method is used to analyze the forced vibration characteristics of the rotating disk. Power spectral density diagrams of the forced vibrations with both one and multiple excitation forces are plotted.