Consider the forward (direct) extrusion of an aluminum rod using 90 degree die. Billets 200 mm in diameter and 400 mm long are being extruded into rods with a diameter of 18 mm. In order to increase the length of the product by 2 m, determine whether it be more economical in terms of pressure to increase the bullet length.

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?