The physics of spinal manipulation: work-energy and impulse-momentum principles.

The purpose of this article was to illustrate that the work-energy and impulse-momentum relations are derived from Newton's second law, and, thus, will give identical results to F = ma for any force system analysis. It should be noted that using the work-energy or the impulse-momentum approach requires that all external forces acting on a system are considered. Furthermore, it must be emphasized that any force acting internal to the system (e.g., muscular forces in the system "chiropractor") do not enter these equations.