Steel balls 12 mm in diameter are annealed by heating to 1150 K and then slowly cooling to 400 K in an air environment for which T = 325 K and h = 20 W/m2 K. Assuming the properties of the steel to be k = 40 W/m K, p = 7800 kg/m3, and c = 600 J/kg K
The air temperature increases with time as T(t) 325 K + at where a = 0.1875 K/s.
Sketch the ball temperature versus time for 0< t < 1 h. Also show the ambient temperature, T, in your graph. Explain special features of the ball temperature behavior.