Unit 2 Test Questions

1. A 3 kg block of copper (c = 385 J/kg·K) at 120°C is placed in 1.5 kg of water at 25°C. Find the final temperature assuming no heat loss.
2. A gas absorbs 800 J of heat and does 300 J of work. Calculate the change in internal energy.
3. Determine the efficiency of a Carnot engine operating between 500 K and 300 K.
4. A refrigerator removes 400 J of heat from the cold compartment while consuming 100 J of work. Find the COP and heat expelled to the hot reservoir.
5. Explain why the second law of thermodynamics implies that entropy increases in spontaneous processes.
6. A gas undergoes an isothermal expansion doing 600 J of work. Calculate the heat exchanged.
7. Discuss why real engines cannot achieve 100% efficiency, using thermodynamic reasoning.
8. Calculate the entropy change when 250 J of heat is added to a system at 500 K.
9. Draw an energy flow diagram for a heat engine absorbing 1000 J from the hot reservoir and rejecting 400 J to the cold reservoir.
10. Describe a real-world application of thermodynamics principles in everyday life.