MATERIAL PARTICLE AND MATERIAL POINT TO HERTZ
Author: Nicolae Mazilu
Published on Friday, March 21st, 2008 in category ProtoQuant
Material Point: The Model of Reality Around Us
When describing the bodies around us, we model them as regular geometrical shapes, usually spheres, omnipresent in Nature at a certain space scale. More precisely, the space scale we are talking about is that where it has been felt that the bodies act upon each other even though they are not in direct contact. This is the scale of action at distance. In dealing with the action at distance Classical Dynamics abstracts even further the regular geometrical representation of bodies, by reducing them to points suggested by these shapes and depending, of course, on the factor distance. In the description of Kepler motion representing the motion of planets, for instance, the mathematical model works with material points. This model of motion was so successful because, when compared with the distance between them, the Sun and the planets can indeed be considered points, in the sense that they are of negligible extension with respect to their distance apart. While this abstraction of the essential quality needed in developing the mathematical tool is a very successful method of Natural Philosophy, when describing the respective bodies directly, i.e. exactly as the fall under our senses, Science usually does not apply the same considerations. It is like the objects under contemplation are again individually into existence, independently of the universal gravitation that governs their motion and existence. This is an unhappy situation, occurring from the way the action at distance is conceived: it is conceived as a force, whose action point must be a … point! Here the Science created the point of application of the force, whereby that force is the global counterpart of a system of partial forces acting upon the components of the extended body or, more on the subject, of forces acting upon whatever we may imagine as components of the extended body. Thus we have, for instance, the concept of center of gravity as being the point of application of the sum of forces of gravitation acting upon the molecules of a body. In considering such a center, we usually think along the line that the forces acting on the body are parallel. This fact completely disregards the essence of the attractive body.