In turning - feed marks with a single point cutting tool approximately how we can calculate the theoretical surface roughness ra'?

Around steel bar, 20 mm in diameter and 400 mm long, is placed concentrically within a brass long. tube which has an outside diameter of 30 mm and thickness 4 mm. the tube is 400 mm the upper end of the vertically placed compound bar is rigidly fixed and a collar is fitted to the bottom end. the application of a load p results in the compound rod storing a total of 5 j of energy.calculate (a) the gradually applied load; (b) the suddenly applied load; (c) the impact load that falls 100 mm and induces 5 j of energy; (d) the instantaneous stresses in both materials; and (e) the instantaneous elongation of the compound rod (egt = 200 gpa and egr = 100 gpa).