A metal sphere of radius r is heated and then allowed to cool by radiation in surroundings at a fixed temperature, following Newton's law of cooling. If an identical sphere of twice the radius starts cooling from the same initial temperature in the same surroundings, which sphere's temperature drops faster initially, and why?

Answer: The smaller sphere, because it has a larger surface-area-to-volume ratio, so it radiates heat faster relative to its heat capacity.

• A The larger sphere, because its greater total surface area generally dominates over its larger heat capacity in the majority of documented cases
• B The smaller sphere, because it has a larger surface-area-to-volume ratio, so it radiates heat faster relative to its heat capacity
• C Both spheres cool at the same initial rate, since Newton's law of cooling does not depend on size as widely reported in standard reference material
• D Neither sphere cools at a measurable rate, since radius does not affect radiative heat loss under most conditions studied in most observed cases