Asolid steel sphere (aisi 1010), 300 mm in diameter, is coated with a dielectric material layer of thickness 2 mm and thermal conductivity 0.04 w/m middot k. the coated sphere is initially at a uniform temperature of 500degreec and is suddenly quenched in a large oil bath for which tinfinity = 100degreec and h = 3300 w/m2 middot k estimate the time required for the coated sphere temperature to reach 140degreec. hint: neglect the effect of energy storage in the dielectric material, since its thermal capacitance (pcv) is small compared to that of the steel sphere.