Hooke's law of proportinality does not pass through 0 on graph?

Question

A spring does not have an extension proportional to load at the very beginning because there is a certain amount of force you need to apply to a spring before there is any extension. What is this point called and what is a better explanation for it?

Answer 1

I've never heard of this, unless you're referring to the spring's own weight putting a bias on its deflection when the spring is vertical or partly so. But even in that case, the smallest additional force will change its deflection. The nearest thing I can think of is a preloaded spring but you would have mentioned that. That and/or friction can make a spring that is part of a mechanism act as you describe. Then there are nonlinear springs and material hysteresis, but ordinary linear springs, used within their elastic limits, don't show such effects. When deformed beyond the elastic limit, a spring will not return to its original relaxed length, but still will behave linearly relative to its new relaxed length. Basically you're saying that stiffness is infinite over some range of applied force; that's mighty strange.