A10 cm thick brick wall is initially at a uniform temperature of 240 °c. at time t = 0, both the surface of the wall are subjected to convective cooling into an ambient at temperature 40 °c with a heat transfer coefficient of 60 w/m2 .k. the following physical properties of the brick are available: k = 0.69 w/m. k; ρ = 2300 kg/m3 and cp = 0.6 j/g. k i. determine the time require to reach the midplane temperature 64 °c. ii. after 2 hours what will be the temperature of the plane 1 cm from the outer surfaces.