Question

A very thin metallic shell of radius r is heated to temperature t and then allowed to cool. the rate of cooling of shell is proportional to.

• A. rT
• B. $\frac{1}{r}$
• C. $r^2$
• D. $r^0$

Answer 1

The correct option is D $r^0$

According to NEWTON"s law of cooling

$\frac{dT}{dt}\propto T-T^{\prime }$

$i.e$ rate of cooling is independent of radius of shell.

Hence $r^0$ is answer.