A hollow copper sphere S and a hollow copper cube C, both of negligible thin walls of same area, are filled with water at `90° C` and allowed to cool in the same environment. The graph that correctly represents their cooling is

Options

A.
B.
C.
D.

Answer

C

Explanation

As `(d theta)/(dt)=(epsilon A sigma)/(mc) 4 theta^3 Delta theta`
For given sphere and cube `( epsilon A sigma)/(mc) 4 theta^3 Delta theta` is constant `(d theta)/(dt)` = constant.