The effect of stress concentration and of deflection in the spring , when the modulus of rigidity is 80 kN/mm2.

Question

A closely – coiled helical spring is made of 10 mm diameter steel wire, with the coil consisting of 10 turns with a mean diameter 120mm. The spring carries an axial pull of 200N. What is the value of shear stress induced in the spring neglecting the effect of stress concentration and of deflection in the spring , when the modulus of rigidity is 80 kN/mm².                            

         (a) 63.5 N/mm² and 34.6 mm

         (b) 54.2 N/mm² and 34.6 mm

         (c) 72.5 N/mm² and 34.6 mm

         (d) 31.6 N/mm² and 56.3 N/mm²