Problem 3. In an annealing process, a 50-mm-thick stainless steel plate (p = 8238 kg/m³, Cp = 468 J/kg.K, k = 13.4 W/mK, and a = 3.48 × 10-6 m²/s) was reheated in a furnace from an initial uniform temperature of 230°C. The ambient temperature inside the furnace is uniform at 1000°C, and the convection heat transfer coefficient is 215 W/m²K. If the entire stainless steel plate is to be heated to at least 600°C, determine the time that the plate should be heated in the furnace using the analytical one-term approximation method.

Fig: 1