  The Slinky is a well-known example of a highly flexible helical spring,
exhibiting large, geometrically nonlinear deformations from minimal applied
forces. By considering it as a system of coils that act to resist axial,
shearing, and rotational deformations, we develop a discretized model to
predict the equilibrium configurations of a Slinky via the minimization of its
potential energy. Careful consideration of the contact between coils enables
this procedure to accurately describe the shape and stability of the Slinky
under different modes of deformation. In addition, we provide simple geometric
and material relations that describe a scaling of the general behavior of
flexible, helical springs.
