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. In an adiabatic expansion ( Δ Q = 0 ), the gas does work on the surroundings ( W > 0 ), reducing its internal energy ( Δ U = -W ). For an ideal gas, U depends only on temperature, so temperature decreases. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W =