Stainless-steel ball bearings ( = 8085 kg/m 3 and c p = 0.480 kJ/kgC) having a diameter

Stainless-steel ball bearings (ρ = 8085 kg/m³ and c_p = 0.480 kJ/kg·°C) having a diameter of 1.8 cm are to be quenched in water at a rate of 1100 per minute. The balls leave the oven at a uniform temperature of 900°C and are exposed to air at 20°C for a while before they are dropped into the water. If the temperature of the balls drops to 850°C prior to quenching, determine 

(a) The rate of heat transfer from the balls to the air 

(b) The rate of entropy generation due to heat loss from the balls to the air.