Practice question

**Quasi-static process** infinitely slow, system always near equilibrium, reversible, can be represented as continuous path on P-V diagram, non-quasi-static rapid process non-equilibrium, work W = ∫ P_ext dV, for quasi-static P_ext = P_system, work = ∫ P dV, zeroth law ensures temperature defined throughout quasi-static. First Law: Δ Q = Δ U + Δ W . Δ Q = -810 (heat released), Δ W = -270 (work on system). -810 = Δ U - 270 ⇒ Δ U = -810 + 270 = -540 J . Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal