Why is the work done path-dependent in thermodynamic processes?
**Cyclic work** equals area inside loop, for rectangular cycle P₁V₁→P₂V₁→P₂V₂→P₁V₂→P₁V₁, W = (P₂-P₁)(V₂-V₁), heat absorbed and rejected during different legs, net work output for heat engine, input for refrigerator. Work ( Δ W = P Δ V ) depends on the pressure-volume path taken, as different paths between the same initial and final states involve different P and Δ V combinations. Unlike internal energy, work is not a state function. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1 -
Ref: NCERT > Physics Book > Thermodynamics > Cyclic Processes and Reversibility Concepts
