During air cooling of steel balls, the convection heat transfer coefficient is determined experimentally as a function of air velocity to be h = 17.9V^0.54 for 0.5 < V < 2 m/s, where h and V are in W/m²∙K and m/s, respectively. Consider a 24-mm-diameter steel ball initially at 300°C with a thermal conductivity of 15 W/m∙K. The steel balls are cooled in air at 10°C and a velocity of 1.5 m/s. Determine the initial values of the heat flux and the temperature gradient in the steel ball at the surface.