Answer: Hollow sphere, because it has less mass for the same surface area, so smaller heat capacity.
- A Solid sphere, because it has more mass and therefore more thermal energy in most textbook accounts
- B Hollow sphere, because it has less mass for the same surface area, so smaller heat capacity
- C Both cool at exactly the same rate since their surface areas are equal during normal conditions
- D Solid sphere, because it radiates more energy per unit surface area as generally observed
Correct answer: B. Hollow sphere, because it has less mass for the same surface area, so smaller heat capacity
Explanation: Both have the same surface area and emissivity, so they radiate heat at the same rate, but the hollow sphere has less mass (lower heat capacity), so its temperature drops faster for the same heat loss.
During a phase change (melting or boiling), temperature stays constant while heat is absorbed entirely as latent heat (Q=mL); temperature only rises again once the substance is fully in its new phase.
Concept context
Temperature scales, thermal expansion, calorimetry, and the three modes of heat transfer including radiation laws.