Long cylindrical steel rods ( = 7833 kg/m3 and cp = 0.465 kJ/kgoC) of 8-cm diameter are

Long cylindrical steel rods (ƿ = 7833 kg/m3 and cp = 0.465 kJ/kg·oC) of 8-cm diameter are heat-treated by drawing them at a velocity of 2 m/min through an oven maintained at 900oC. If the rods enter the oven at 30oC and leave at a mean temperature of 700oC, determine the rate of heat transfer to the rods in the oven.