A helical compression spring is wound with a 4 mm diameter music wire with squared and ground ends. The spring has 11 total coils, an outside diameter of 30 mm and a free length (height) of 70 mm. Use G=79.3GPa,Sse​=310MPa,A=2170, m=0.146, Syt​=0.75 Sut​,Ssy​= 0.577 Syt​, the number of inactive coils is 2 .
Determine: a) The spring modulus (stiffness).