Topic: Thermodynamics
A 10 kg solid at 100 C with a specific heat of 0.8 kJ/kg C is immersed in 40 kg of 20 C liquid with a specific heat of 4.0 kJ/kg C. Estimate the temperature after a long time if the container is insulated (Specific heat of water 4.18 kJ/kg).
- A. 30 C
- B. 28 C
- C. 26 C
- D. 24 C
Answer: D. 24 C
Explanation: Using the principle of conservation of energy, the heat given by the solid equals the heat taken by the liquid: 10 * 0.8 * (100 - t) = 40 * 4.0 * (t - 20). Simplifying this gives 800 - 8t = 160t - 3200. Solving for t yields 168t = 4000, so t = 23.8 C, which rounds closely to 24 C.