The equivalent stiffness of two springs of stiffness $$S_{1} and S_{2}$$ joined in sereies is given by S =

A

$$\frac{S_{1} S_{2} }{S_{1}+S_{2}}$$

B

$$\frac{\frac{S_{1}}{S_{2}}}{S_{1}+S_{2}}$$

C

$$ {S_{1}+S_{2}}$$

D

$$ S_{1} S_{2} $$