Q. A hollow copper sphere $S$ and a hollow copper cube $C$, both of negligible thin walls of same area, are filled with water at $90℃$ and allowed to cool in the same environment. The graph that correctly represents their cooling is
A)
B)
C)
D)
Explanation
(c) $\frac{d\theta}{dt} = \frac{\varepsilon A\sigma}{mc}4\theta_{0}^{3}\mathrm{\Delta}\theta$
For given sphere and cube $\frac{\varepsilon A\sigma}{mc}4\theta_{0}^{3}\mathrm{\Delta}\theta$ is constant so for both rate of fall of temperature $\frac{d\theta}{dt} =$ constant
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.