Practice question

**First law of thermodynamics** ΔU = Q - W, ΔU internal energy change (J), Q heat added to system (J), W work done by system (J), sign convention physics Q positive when added, W positive when done by system, energy conservation, for isochoric W=0 ΔU=Q, for adiabatic Q=0 ΔU=-W, for isothermal ΔU=0 Q=W, for cyclic ΔU=0 Q_net=W_net. Δ Q = m s Δ T . m = 0.3 , s = 236.1 , Δ T = 65 - 35 = 30 . Δ Q = 0.3 × 236.1 × 30 = 2124.9 J ≈ 2125 J . Using first law ΔU = Q - W,