Arabic and Latin science of weights
In this chapter Latin and Arabic Middle Ages mechanics are compared, both based on virtual displacements VWLs. In the first part Arabs are considered who, with Thabit ibn Qurra, use as a principle of equilibrium a VWL for which the effectiveness of a weight on a scale is proportional to its virtual displacement measured along the arc of the circle described by the arm from which the weight is suspended. In the second part Latin scholars are considered who, with Jordanus de Nemore, assume as principles two distinct VWLs. A VWL is associated with the concept of gravity of position for which the efficacy of a weight on a scale is the greater the more its virtual displacement is next to the vertical. Another VWL is associated with the resistance of a weight to be lifted, which depends on the lifting entities in a given time. In formulas: What can raise a weight p of a height h can raise p/n of nh.