20.8 (USCS units) The shear strength of a certain work mate- rial = 50,000 lb/in². An orthogonal cutting operation is performed using a tool with rake angle = 20° at a

cutting speed 100 ft/min, chip thickness before the cut = 0.015 in, and width of cut = 0.150 in. The resulting chip thickness ratio = 0.50. Determine (a) the shear plane angle, (b) shear force, (c) cutting force and thrust force, and (d) friction force. 20.9 (USCS units) Solve the previous problem, except that the rake angle has been changed to -5° and the resulting chip thickness ratio = 0.35.