C) In a production turning operation, the machining of a part must be completed in a total time of 15 minute. The original cylindrical piece dimensions are 400 mm long, and 150 mm in diameter. The final dimensions of the work piece are 400 mm long & 86 mm in diameter. Using a feed of (0.3 mm/rev.) and a depth of cut (2 mm). At what Spindle rotational speed must be used to meet the machining time requirement. (10 Marks)