Four solid spheres are made of the materials listed below. determine the maximum diameter of each so that the lumped capacitance model can be used to find t(t) for heating each in an oil bath with h=159 w/ m k . a. aisi 316 stainless steel b. copper c. cement mortar, table a.3 d. expanded polystyrene molded beads (styrofoam), table a.3 note: assume constant k for the solids at 300 k.