Mechanical interpretation of existence theorems in a nonlinear Dirichlet problem

The existence of radial solutions of a nonlinear Dirichlet problem in a ball is translated to the language of Mechanics, i.e. to requirements on the time of motion of a particle in an external potential and under the action of a viscosity force. This approach reproduces existing theorems and, in principle, provides a method for the analysis of the general case. Examples of new theorems are given, which prove the usefulness of this qualitative method.