Question: A large steel plate (with a thermal diffusivity of 1.3 × 10-5 m2/s and a thermal conductivity of 40 W/m·K) is 3 cm thick. At zero time it begins to receive heat on one side at the rate of 100 kW/m2 while the other side is exposed to a fluid at -20 °C with a heat transfer coefficient of 500 W/m2 ·K. If the initial temperature of the entire plate is 40 °C, determine the temperature at the midplane after 5 s.