Consider a spherical reactor of 5-cm diameter operating at steady condition has a temperature variation that can be expressed in the form of T(r) = a - br², where a = 850°C and b = 5 × 10⁵ K/m². The reactor is made of material with c = 200 J/kg·°C, k 5 40 W/m·K, r = 9000 kg/m³. If the heat generation of reactor is suddenly set to 9 MW/m³, determine the time rate of temperature change in the reactor. Is the heat generation of reactor suddenly increased or decreased to 9 MW/m³ from its steady operating condition?