= 1. A spherical piece of aluminum (k = 237 W/mK, p = 2.7 g/cm', Cp = 0.89 J/gK) weighing 5.5 kg and initially at a temperature of 305C is suddenly immersed in a fluid at 12C. The convection heat transfer coefficient is 42 W/m2 C. Estimate the time required to cool the center of the aluminum to 95C