. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "A group of Component_entities along with their interrelations is viewed as a Complex.\nBy definition, no external forces act upon an isolated system of particles.\nEarth is a contained system which receives energy from the sun."^^ . . . . . . . . . . . . . . . "frame"^^ .