This change of stuff is also called flow . For instance, in electrical systems, dynamic behaviour consists of the change of electrical charge , i.e. electrical current . Likewise, in the mechanical domain the stuff is called location and change of location is velocity . The thing required to bring about a flow is called effort . In each domain, dynamic behaviour is described as flow, i.e. change of stuff.
Effort is that what is required to bring about a flow.
Physical behaviour can therefore be defined in terms of energy flows. The process ontology introduces physical mechanisms which are applications of physical laws or principles to one or more energy flows. An important feature of these mechanisms is that they exploit in detail the analogies that exist between different physical domains. For example, the principle of conservation of momentum in mechanics is analogous to induction in the electrical domain. Many more of these analogies exist.