SPRINGS attached in series

[hassam]

can anyone help me understand this......esp. the expression for compressed distance

 

[beacon_of_light]

I believe you don't need to know how to derive it ... it's just a simple rule...
Fo springs in series,

1/Keq = 1/K1 + 1 /K2

For springs in parallel combination,

Keq = K1 +K2