Question

The opposite faces of a cubic block of iron of cross-section area $4c{m}^2$ are kept in contact with steam and melting ice. The quantity of ice melting at the end of $10$ min will be :
(Given: $K_{iron}$$=0.2$ CGS units)

• A. 700g
• B. 500g
• C. 300g
• D. 100g

Answer 1

The correct option is C 300g

The heat transfer equation is given by:
$\dot{Q}=KA\frac{\Delta T}{l}$
The heat flows for 10min, i.e. heat absorbed by ice = $600\dot{Q}$ (600 seconds = 10 minutes)
This heat flow is equal to the latent heat of fusion times the mass of melted ice.
$600\dot{Q}=600KA\frac{\Delta T}{l}=m_{melted}{L}_{fusion}$
i.e.
$m_{melted}=600KA\frac{\Delta T}{L_{fusion}l}=600\times 0.2\times \left(4\right)\frac{100}{2\times 80}=300g$