A sphere, a cube and a disc all of the same material, quality and volume are heated to 900 K and left in air. Which of these will have the lowest rate of cooling
- A. Cube
- B. Disc
- C. Sphere
- D. All will have the same rate of cooling
Answer: C. Sphere
Explanation: Cooling rate is proportional to Surface Area / Volume. For a given volume, a sphere has the minimum surface area, thus the slowest cooling rate.