A conservative force is a force which is path-independent. In other words, in moving an object from point A to point B, the total work done is independent of the path that the object took. The term conservative force comes from the fact that when a conservative force exists, it is possible to definepotential energy which is in many cases more convenient quantity than force. The fundamental forces, such as gravity, are all conservative. In physics, a force is what changes the velocity of a material body. ... Work (abbreviated W) is the path integral of a force along given path. ... Potential energy (U, or Ep) is defined as work of conservative force(s) during change of state of physical system from given static state to another static state (latter is usually called reference state, or reference level). ... A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. ... It has been suggested that Law of universal gravitation be merged into this article or section. ...

Nonconservative forces arise due to neglected degrees of freedom. For instance, friction may be treated without resorting to the use of nonconservative forces by treating heat as kinetic energy; however that means every molecule's motion must be considered rather than handling it through statistical methods. For macroscopic systems the nonconservative approximation is far easier to deal with than millions of degrees of freedom.An example of a non-conservative force is friction. The phrase degrees of freedom is used in three different branches of science: in physics and physical chemistry, in mechanical and aerospace engineering, and in statistics. ... A red-hot iron rod cooling after being worked by a blacksmith. ... In physics, friction is the non-conservative resistive force that occurs when two surfaces travel along each other when forced together. ...