Frooom! Fooooo Figure 1 F microns F (force) coils Ak X (deflection) Gd4 8D na The spring constant for a helical coil spring is Gd4 predicted by: k = where G is the material 8D na modulus, d is the wire diameter, D is the mean diameter of the coil and na is the number of coils. -D- Assume the following spring properties and measurements and determine k in N/m. G = 95 kN/mm OD = 14 mm Figure 2 d = 1400 na = 69 Recall the coil mean diameter D is slightly different from the outside coil diameter OD, Report the result with at least 3 significant figures,