Question

A 5cm thick ice block is there on the surface of water in a lake. The temperature of air is $-{10}^{\circ }$ C; how much time it will take to double the thickness of the block
$(L=80cal/g,K_{ice}=0.004Erg/s-k,d_{ice}=0.92gc{m}^{-3})$

• A. 1 hour
• B. 191 hours
• C. 19.1 hours
• D. 1.91 hours

Answer 1

The correct option is C

19.1 hours

$t=\frac{Ql}{KA({\theta }_1-{\theta }_2)}=\frac{mLl}{KA({\theta }_1-{\theta }_2)}=\frac{V\rho Ll}{KA({\theta }_1-{\theta }_2)}$
$=\frac{5\times A\times 0.92\times 80\times \frac{5+10}{2}}{0.004\times A\times 10\times 3600}=19.1hours.$