A spherical metal ball of radius r0 is heated in an oven to a temperature of 600F throughout and is then taken out of the oven and allowed to cool in ambient air at 78F. The thermal conductivity of the ball material is 8.3Btu/hftF, and the average convection heat transfer coefficient on the outer surface of the ball is evaluated to be h=4.5Btu/hft2F. The emissivity of the outer surface of the ball is 0.6 , and the average temperature of the surrounding surfaces is Tsurr=525 R. Assuming the ball is cooled uniformly from the entire outer surface, express the initial and boundary conditions for the cooling process of the ball