일반물리학 1 — Entropy and the Second Law of Thermodynamics: Problem 39

39 In an experiment, 400 g of aluminum (with a specific heat of $900 \text{ J/kg} \cdot \text{K}$) at $100^{\circ}\text{C}$ is mixed with $50.0 \text{ g}$ of water at $20.0^{\circ}\text{C}$, with the mixture thermally isolated. (a) What is the equilibrium temperature? What are the entropy changes of (b) the aluminum, (c) the water, and (d) the aluminum–water system?