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),
UNIT to be some kind of covert counter-terrorist unit. Although the Brigadier originally states that UNIT do not arrest people, as of the 21st century, UNIT has the authority to detain persons indefinitely without trial, appeal, outside contact or legal representation, as experienced by Toshiko Sato before she was recruited to work for the British government by the Torchwood Institute in a flashback in the "Torchwood" episode "Fragments" (2008). The organisation was rearranged by Kate Stewart, the daughter of Brigadier Lethbridge-Stewart. In "The Power of Three" (2012), Kate heads UNIT's scientific research department, which now has authority over the military branch.