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 $1000°C$ . Which one of these will cool first
IIT 1972, Medium
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(a) Rate of cooling $\frac{{\Delta \theta }}{t} = \frac{{A\varepsilon \sigma ({T^4} - T_0^4)}}{{mc}}$
==> $\frac{{\Delta \theta }}{t} \propto A$. Since area of plate is largest so it will cool fastest.
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