The stiffness of the close coil helical spring is
A. $$\frac{{{{\text{d}}^4}{\text{N}}}}{{8{{\text{D}}^3}{\text{n}}}}$$
B. $$\frac{{{{\text{d}}^4}{\text{N}}}}{{4{{\text{D}}^3}{\text{n}}}}$$
C. $$\frac{{4{{\text{D}}^3}{\text{N}}}}{{{{\text{d}}^4}{\text{n}}}}$$
D. $$\frac{{8{{\text{D}}^3}{\text{N}}}}{{{{\text{d}}^4}{\text{n}}}}$$
Answer: Option A
Stiffness of helical spring, K=Gd^4/8D^3n N/mm.
No cmmnts