The two connected cylindrical rods above have the following values for their dimensions: d1 = 48 mm d2 = 23 mm l1 = 1.7 m l2 = 0.9 m if, f1 = 122 kn f2 = 61 kn find the average normal stress (σ) for the mid-section of rod bc. include the correct sign for your answer. calculate your answer to one decimal place, and make sure that the absolute value is between 0 - 999, with the appropriate unit. (in other words, if you use the correct unit, your answer's absolute magnitude will be between 0 - 999.)