Q. Ice starts forming in a lake with water at 0$℃,\ $when the atmospheric temperature is $- \ 10℃.\ $If time taken for 1 cm of ice to be formed is 7 h, the time taken for the thickness of ice to increase from 1 cm to 2 cm is
A) 7 h
B) Less than 7 h
C) More than 7 h but less than 14 h
D) More than 14 h
Explanation
(d) Growth of ice in a pond is conduction process governed by the relation $t = \ \frac{\rho L}{K\theta}\frac{y^{2}}{2}$
The ratio of times for thickness of ice from 0 to $y;\ y\ to\ 2\ y$ = 1 : 3
$\therefore\ \ $Time taken to increase the thickness from 1 cm to 2 cm is equal to 3$\times 7 = 21\ $h.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.