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),
Work of breathing narcotic effects. Standards for these conditions exist and to make useful comparisons between breathing apparatus they must be tested to the same standard. Factors which influence the work of breathing of an underwater breathing apparatus include density and viscosity of the gas, flow rates, cracking pressure (the pressure differential required to open the demand valve), and back pressure over exhaust valves. The ANSTI machine is used for automated testing of underwater breathing apparatus. Work of breathing Work of breathing (WOB) is the energy expended to inhale and exhale a breathing gas. It is usually expressed as work per unit volume,