The spring constant for a helical coil spring, k theoretically follows the form shown where d lower case is the wire diameter, D UPPER CASE is the mean diameter of the coil, na is the number of active coils and G is a material property called the shear modulus.

Out side diameter OD mm

Wire diameter d microns

Active coils na

modulus G kNsqmm

Also assume that all the measurements have an uncertainty of of the average. Use the HighLow method to determine a k and b deltak the uncertainty in k in Nm

What is k and delta k