Question

A sphere, a cube and a thin circular plate all made of the same material and having the same mass are initially heated to a temperature of 200°C. Which of these objects will cool fastest and which one slowest when left in air at room temperature. Give reasons.

Answer 1

The thin circular plate has the largest surface area. The sphere has the smallest surface area. Thus the plate will radiate maximum heat while the sphere will radiate minimum heat. Hence the plate will cool fastest and the sphere will cool slowest.