There is formation of layer of snow $x\,cm$ thick on water, when the temperature of air is $ - {\theta ^o}C$ (less than freezing point). The thickness of layer increases from $x$ to $y$ in the time $t$, then the value of $t$is given by
A$\frac{{(x + y)(x - y)\rho L}}{{2k\theta }}$
B$\frac{{(x - y)\rho L}}{{2k\theta }}$
C$\frac{{(x + y)(x - y)\rho L}}{{k\theta }}$
D$\frac{{(x - y)\rho Lk}}{{2\theta }}$
Medium
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A$\frac{{(x + y)(x - y)\rho L}}{{2k\theta }}$
a (a) Since $t = \frac{{\rho L}}{{2k\theta }}(x_2^2 - x_1^2)$
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