 The first form is an epispiral; the second is a Poinsot's spiral; the third form is a hyperbolic spiral, which can be seen as the limiting case between an epispiral and a Poinsot's spiral; the fourth is the equiangular spiral.Cotes's spirals appear in classical mechanics, as the family of solutions for the motion of a particle moving under an inverse-cube central force.Consider a central force

where "μ" is the strength of attraction.