Problem 6 (10points) Resistance Spot-Welding operation is used to weld two metal sheets 4 mm thickness of each and 11 J/mm unit melting energy. The weld nugget is formed with 6 mm in diameter and 5.0 mm thick to provide the required strength of the joint. If the weld duration and minimum current level are set as 0.5 sec and 8,000 A, the heat transfer efficiency (/) and melting efficiency (77) will be 45% of the total electrical energy generated to be used to create the weld nugget (the rest being dissipated). Determine the electrical resistance between the two metal surfaces