Problem 1: a low-carbon steel billet is 75 mm long with diameter = 35 mm. it is direct extruded to a diameter = 20 mm using an extrusion die angle = 75˚. the steel’s strength coefficient = 500 mpa, and its strain hardening exponent = 0.25. in the johnson extrusion strain equation, a = 0.8 and b = 1.4. determine (a) true strain in ideal condition (no redundant work); (b) extrusion strain by johnson equation; and (c) l (remaining billet length) when the metal just reaches the exit of the die; and (d) ram pressure and force at l = 70 and l = 10 mm (hints: there is friction).