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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 3000°K, which of these will cool fastest?

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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 3000°K, which of these will cool fastest? Answer: Plate

The rate of cooling of a body depends on its surface area to volume ratio (A/V). For the same mass and material, the body with the largest surface area will lose heat the fastest. A thin circular plate has the greatest surface area compared to a sphere or cube of the same mass, so it cools fastest according to Newton’s law of cooling.

Question context

This question is part of ⚙️ Mechanical Eng within the broader 🛠️ Engineering Essentials subject and appears in the SPSC – Sindh Public Service Commission preparation collection. Reviewing the answer together with nearby questions helps reinforce the underlying concept and identify how it may appear in competitive exams.