Work (thermodynamics) of the energy went out as heat, and how much as work. This can be summarized by saying that heat and work are not state functions of the system. This is in contrast to classical mechanics, where net work exerted by a particle is a state function. Pressure–volume work (or "PV" work) occurs when the volume of a system changes. "PV" work is often measured in units of litre-atmospheres where = . However, the litre-atmosphere is not a recognised unit in the SI system of units, which measures P in Pascal (Pa), V in m, and PV in Joule (J),
Energy slave "Man and Energy", but the term did not come to be widely used until the 1960s, and is generally credited to Fuller. An energy slave is used to compare the productivity of a person and the energy that would be required to produce that work in the modern, oil fuelled industrial economy, although it could be applied anywhere that labor is produced with non-human sourced energy. It does not include the ancillary costs of damage to the environment or social structures. Formally, one energy slave produces one unit of human labor through the non-human tools and energy supplied by the