Why W = -PV?
GeneralClass 12AllAnswered 27 Mar 2026
Answer
The euation W = -PV (more accurately W = -PΔV) uses a negative sign due to sign convention in thermodynamics. When a system expands against external pressure, it performs work on the surroundings, losing energy (negative W). When compressed, work is done on the system, adding energy (positive W). This convention ensures energy conservation: energy leaving the system is negative, energy entering is positive.
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