where m is the test particle mass, α α is a factor representing the nonlinearity of the theory, q 5 is the test particle's fifth-force charge, and u μ μ = d x μ μ / d s is its four-velocity. Assuming that the fifth-force charge is proportional to mass, i.e., q 5 = κ κ m , the value of κ κ = G N / ω ω is determined and the following equation of motion is obtained in the spherically symmetric, static gravitational field of a point mass of mass M :