A sphere, a cube and a thin circular plate, all made of same material and having same mass are initi

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10-2.Transmission of Heat

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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 $1000°C$ . Which one of these will cool first

A

Plate

B

Sphere

C

Cube

D

None of these

(IIT-1972)

Solution

(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.

Standard 11

Physics

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