$*($use three elements$)\backslash \backslash$The base plate of an iron is $0\mathrm{.}6$ cm thick. The plate is subjected to $100$ W of power $($provided by resistance heaters inside the iron, as shown in Figure P$13-15),$ over a base plate cross$-$sectional area of $250c{m}^2,$ resulting in a uniform flux generated on the inside surface. The thermal conductivity of the metal base plate is $k=20\frac{W}{m}-C.$ The outside ambient air temperature is $20C$ with a heat transfer coefficient of $20\frac{W}{m^2}-C$ at steady$-$state conditions. Assume one$-$dimensional heat transfer through the plate thickness. Using three elements, model the plate to determine the temperatures at the inner surface and interior one$-$third points.

Figure P$13-15$