Solve the below problem:
Q: A thick oak wall, initially at 25°C, is suddenly exposed to combustion products for which T8 = 800°C and h=20W/m2 · K.
(a) Determine the time of exposure required for the surface to reach the ignition temperature of 400°C.
(b) Plot the temperature distribution T(x) in the medium at t = 325 s. The distribution should extend to a location for which T = 25°C.