Stainless steel ball bearings (rho = 8085 kg/m3 and cp = 0.480 kj/(kg◦c)) having a diameter of 1.5 cm are to be quenched in water at a rate of 900 per minute. the balls leave the oven at a uniform temperature of 1000◦c and are exposed to air at 25◦c for a while before they are dropped into the water. if the temperature of the balls drops to 900◦c prior to quenching, determine the rate of heat transfer from the balls to the air.