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Work

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For work in the economic sense, see: Employment.

In physics, work, along with heat, is one of the two quantities that are products of energy transfer across the boundary of a system. Work itself is a broad term, but in thermodynamics is defined as: something done by a system if the sole external effect on the surroundings could be the raising of a weight.1 In the United States, work units are in foot pound force (ft-lbf), while in SI units work is in units of Joules (J) which is kilogram multiplied by meters squared and divided by seconds squared (kg*m^2/s^2).

Conventions for positive and negative work need to be kept consistent. Consistency is more important than sign conventions, although work done on the surrounds is generally considered positive whereas work done on a system is considered negative. What ever makes most sense to the individual, make sure it is kept consistent.

At what rate work is done is defined by units of power. In the SI system power is in units of watts (W), which itself is defined as joules per second (J/s). In the English system power is in ft-lbf/sec.

Specific work can be found by dividing the work over mass of a substance. Specific terms are in represented by lower case letters. For instance, volume is V whereas specific volume is v.

Work can be calculated by W= PdV =P(V2-V1)=mP(v2-v1)