A rectangular workpiece 320 mm long, 60 mm wide and 56 mm thick is peripheral-milled to a thickness of 50 mm. The cutter is 65 mm in diameter with 4 teeth and overhangs the work on both sides. Cutting speed 0.50 m/s, chip load 0.24 mm/tooth. Taking the approach A = √(d(D − d)), determine (a) the machining time in s and (b) the metal removal rate in mm³/s.