Euler's laws of motion each governed by Newton’s laws of motion, then Euler’s equations can be derived from Newton’s laws. Euler’s equations can, however, be taken as axioms describing the laws of motion for extended bodies, independently of any particle distribution. The total body force applied to a continuous body with mass , mass density , and volume , is the volume integral integrated over the volume of the body: where is the force acting on the body per unit mass (dimensions of acceleration, misleadingly called the "body force"), and is an infinitesimal mass element of the body. Body forces and contact forces acting
Laws of technical systems evolution in TRIZ. The following authors, besides Altshuller, contributed most to it: Yuri Khotimlyansky (studied patterns of energy conductivity in technical systems), Vladimir Asinovsky (proposed principles of correspondence of various components of technical systems), Yevgeny Karasik (co-authored with Altshuller the law of transition from a macro-level to a micro-level, introduced the notion of dual technical systems and studied the patterns of their evolution). In his pioneering work of 1975, Altshuller subdivided all laws of technical systems evolution into 3 categories: Laws of technical systems evolution The laws of technical systems evolution are the most general evolution trends for technical systems discovered