The physics of spinal manipulation. Part I. The myth of F = ma

The product of the adjusting physician's mass and acceleration does not quantify the adjustive force as popularly believed, an error stemming from a misunderstanding of Newton's second law. In this paper, a gedanken experiment illustrates the misapplication of F = ma and suggests that the adjustive force depends on the impact velocity, mass of the doctor, and intrinsic physical properties of the doctor and patient.