In 1977, Richard Feynman, in an invited lecture at the national APS meeting, stated unequivocally that quantum mechanical principles placed few important restrictions on how a stable atom can be held in place, and, indeed, a stable atom on the whole has a comparatively definite position fixed by its comparatively massive nucleus. In this spirit, N-body problems are studied using molecules and classical molecular potentials and also using collections of molecules, called particles, with related potentials derived through conservation of mass and energy. Detailed applications include primary vortex flow and turbulent flow for both water vapor and air, soliton collision, and the motion of a top on a smooth surface. Other applications, like microdrop collision, stress of a slotted copper plate, contact angle of adhesion, cellular self-reorganiztion, the bounce of an elastic ball, and elastic snap-through are mentioned and referenced appropriately. Lastly, numerical methodology is developed which preserves the physics of special relativity and is applied to simulate a relativistic oscillator.