Travel to work area legal status. However, they give planners and geographers an alternate view of urban life as their boundaries are tied not to arbitrary administrative limits but socio-economic ties. Having an idea of where people commute from for work is particularly useful for public transport planning. Travel to Work Areas are defined by the Office for National Statistics using census data for commuting between wards, based on the different locations of individuals' home and work addresses. A Travel to Work Area is a collection of wards for which "of the resident economically active population, at least 75% actually work in the area,
Work (thermodynamics) system is well defined and equal to the pressure exerted by the system on the surroundings. This arrangement for transfer of energy as work can be varied in a particular way that depends on the strictly mechanical nature of pressure–volume work. The variation consists in letting the coupling between the system and surroundings be through a rigid rod that links pistons of different areas for the system and surroundings. Then for a given amount of work transferred, the exchange of volumes involves different pressures, inversely with the piston areas, for mechanical equilibrium. This cannot be done for the transfer of