1. A slab 2L thick, initially at a uniform To, has its surfaces suddenly lowered to temperature Ts. Simultaneously a volumetric heat source Q" is activated within the slab. Show how you would analyze this problem to determine the temperature response. (Hint: Try a superposition of a steady and a transient problem.) 2. A 5mm-thick steel firewall is suddenly exposed to a radiant heat source that can be approximated as a blackbody at 1000 K. How long will it take for the surface to reach 500 K if the initial temperature of the wall is 300 K? 3. A 3cm-diameter rod of a composite material is initially at 30C. It is immersed into a chamber in which saturated steam at 120C condenses on the rod and heats it. When the centerline temperature reaches 110C, the rod is removed and allowed to cool in 20C air until the center falls to 30C. How long does each stage take? Assume a very large heat transfer coefficient for the heating process, and a value of 15 W/m K for the cooling process. Properties of the composite include p = 1500 kg/m, c = 1800 J/kg K, k = 1.2 W/m K.