Consider a 5 -m-long constantan block \((k=23 \mathrm{~W} / \mathrm{m} \cdot
\mathrm{K})\) \(30 \mathrm{~cm}\) high and \(50 \mathrm{~cm}\) wide (Fig. P5-70).
The block is completely submerged in iced water at \(0^{\circ} \mathrm{C}\) that
is well stirred, and the heat transfer coefficient is so high that the
temperatures on both sides of the block can be taken to be \(0^{\circ}
\mathrm{C}\). The bottom surface of the bar is covered with a low-conductivity
material so that heat transfer through the bottom surface is negligible. The
top surface of the block is heated uniformly by a 8-kW resistance heater.
Using the finite difference method with a mesh size of \(\Delta x=\Delta y=10
\mathrm{~cm}\) and taking advantage of symmetry, (a) obtain the finite
difference formulation of this problem for steady twodimensional heat
transfer, \((b)\) determine the unknown nodal temperatures by solving those
equations, and \((c)\) determine the rate of heat transfer from the block to the
iced water.