Stainless steel (AISI 304) ball bearings, which have uni- formly been heated to 850C, are hardened by quench- ing them in an oil bath that is maintained at 40C. The ball diameter is 20 mm, and the convection coefficient associated with the oil bath is 1000 W/m2 K. (a) If quenching is to occur until the surface tempera- ture of the balls reaches 100C, how long must the balls be kept in the oil? What is the center tempera- ture at the conclusion of the cooling period? (b) If 10,000 balls are to be quenched per hour, what is the rate at which energy must be removed by the oil bath cooling system in order to maintain its temper- ature at 40C?