Question

A solid sphere and a hollow sphere of the same material and size are heated to the same temperature and allowed to cool in the same surroundings. If the temperature difference between the surrounding and each sphere is T, then

• A. the hollow sphere will cool at a faster rate for all values of T
• B. the solid sphere will cool at a faster rate for all values of T
• C. both spheres will cool at the same rate for all values of T
• D. both spheres will cool at the same rate only for small values of T.

Answer 1

The correct option is C

both spheres will cool at the same rate for all values of T

The rate at which a sphere radiates heat depends upon its material, its surface area and its temperature. Therefore, the solid and the hollow spheres, being of the same material and of the same size and at the same temperature, will cool at the same rate. Hence, the correct choice is (c).