Advanced Problems

1. A 5 kg block of aluminum (c = 900 J/kg·K) at 150°C is placed in 2 kg of water at 25°C. Calculate the final temperature, assuming no heat loss to surroundings.
2. A Carnot engine operates between reservoirs at 800 K and 300 K. If it absorbs 1200 J of heat from the hot reservoir, calculate the work done and heat expelled.
3. A gas undergoes an isothermal expansion doing 500 J of work. Determine the heat exchanged with the surroundings.
4. Explain, with calculations, why no real engine can exceed the Carnot efficiency.
5. A refrigerator has a COP of 4. It removes 600 J of heat from the cold compartment. Determine the work input and heat released to the hot reservoir.
6. Calculate the entropy change when 200 J of heat is added to a system at 400 K.
7. A 2 kg iron block is heated and then cooled in water. Analyze energy transfer using a problem-solving strategy diagram.
8. Determine the efficiency of a heat engine if 1500 J of heat is absorbed and 600 J is wasted as heat to the cold reservoir.