A thick steel slab (Ï= 7800 kg/m3, c= 480 J/kg·K, k=50 W/m·K) is initially at 300°C and is cooled by water jetsimpinging on one of its surfaces. The temperature of the water is25°C, and the jets maintain an extremely large, approximatelyuniform convection coefficient at the surface. Assuming that thesurface is maintained at the temperature of the water throughoutthe cooling, how long will it take for the temperature to reach50°C at a distance of 28 mm from the surface?
