A) 30 h
B) 18 h
C) 6 h
D) 32 h
Correct Answer: A
Solution :
For growth of ice, we have \[t=\frac{\rho L}{2K\theta }(x_{2}^{2}-x_{1}^{2})\]where, \[\rho \]is density, L latent heat, \[{{x}_{2}},{{x}_{1}}\]thickness and\[\theta \]temperature. Similarly, for second case \[t'=\frac{\rho L}{2K\theta }(x_{4}^{2}-x_{3}^{2})\] \[\therefore \] \[\frac{t'}{t}=\frac{(x_{4}^{2}-x_{3}^{2})}{(x_{2}^{2}-x_{1}^{2})}\] \[=\frac{({{20}^{2}}-{{5}^{2}})}{({{5}^{2}}-0)}\] \[=\frac{375}{25}=15\] \[\therefore \] \[t'=15t=15\times 2=30\,h\]You need to login to perform this action.
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