The figure shows a round shaft mounted in bearings at A and D and having pulleys at B and C. The forces acting on the pulleys, shown on the right, represent the belt pulls. The shaft is to be made of cast iron with S = 170 MPa and S = 670 MPa. If a factor of safety of n = 2.8 is required for the design, what should be the minimum diameter of the shaft (note that the shaft is in static equilibrium)? Bearing 200 mm B Pulley 01501 mm 120 N Pulley C 200 mm 200 mm 150 mm Z 1600 N 225 N 1335 N