ar base plate is fixed at each of its four corners by a 20 mm diameter bolt and nut as w in the Figure. The plate rests on washers of 22 mm internal diameter and 50 mm external diameter. Copper washers which are placed between the nut and the plate are of 22 mm internal diameter and 44 mm external diameter. (a) If the base plate carries a load of 120 kN (including self-weight, which is equally distributed on the four corners), calculate the stress on the lower washers before the nuts are tightened. (b) What could be the stress in the upper and lower washers, when the nuts are tightened so as to produce a tension of 5 kN on each bolt? 44 mm 22 mi 50 mm Upper washer Base plate Lowe washe 20 mm