A sphere, a cube, and a thin circular plate, all of the same material and same mass are initially heated to same high temperature.
a) plate will cool fastest and cube the slowest
b) sphere will cool fastest and cube the slowest
c) plate will cool fastest and sphere the slowest
d) cube will cool fastest and plate the slowest
The answer is the option (c) Plate will cool fastest and sphere the slowest.
Explanation: On cooling, loss of heat is directly proportional to surface area exposed to the surrounding, material of object & temperature difference between the surrounding and the body.
Here, opt (c) is verified as the surface area of the sphere is minimum and thus it will cool slowest, while the surface area of circular plate is maximum, and it will cool fastest.