Answer: 2:1.
- A 1:1
- B 2:1
- C 1:2
- D 4:1
Correct answer: B. 2:1
Explanation: Rate of cooling dT/dt ∝ (surface area)/(volume) ∝ 1/r for spheres of the same material and temperature. Ratio of smaller to larger = (1/r):(1/2r) = 2:1.
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.