Question

A cube, a thin circular plate, and a sphere are made of the same metal and having the same mass and same volume. They are initially heated to the same temperature. When left in air at the room temperature, which of these bodies will cool fastest and slowest respectively?

• A. The cube; the sphere
• B. The circular plate; the cube
• C. The circular plate; the sphere
• D. The sphere; the circular plate

Answer 1

The correct option is A The cube; the sphere

For a given volume, among all the three objects, the sphere has the least surface area and the cube will have the maximum surface area. This is also due to the fact that the volume and mass of all three are the same.

According to Heat theory, the rate of loss of heat is proportional to the surface area of the object. Hence, the rate of cooling will be slowest for the sphere and fastest for the cube.

Thus the correct option is A.