A cylindrical aluminum rod, with an initial length of 0.8200 m and radius 1200.0 µm, is clamped in place at one end and then stretched by a machine pulling parallel to its length at its other end. Assuming that the rod's density (mass per unit volume) does not change, find the force magnitude that is required of the machine to decrease the radius to 1199.9 µm. (The yield strength is not exceeded.)