0-6 solid length is 20 mm. [8 Marks] a) Compute the force required to c ompress the spring to solid height. 14 Marks) 14 Marks b) Compute the free length of the spring. (b) It is required to design a helical torsion spring for a mechanism. The spring wire diameter is 2.25 mm and the mean diameter is 20.5 mm. The ultimate tensile strength, Su 2550MPa. The Yield strength (s) of the material is 60% of the ultimate tensile strength (s) and the factor of safety is 3.0. The maximum bending moment acting on the spring is 500 N-mm. Calculate the bending stress in the spring and compare it with design stress. 7 Marks)