Question

If a helical tension spring consisting of 12 live coils of ¼ inch steel wire and of 1 ¼ inch mean diameter is attached to the end of another helical tension spring of 18 live coils of ¼ inch steel wire and of 1 ¾ inch mean diameter, calculate the largest load (kN) that may be applied to the spring assembly without exceeding a shearing stress of 70 000 psi in the springs