Can Hookes Law work for any elastic material?
No, it only works within limits of strain or deformation, since all materials have such limits. First, if stretched enough, materials break. Second, many materials can have a surprisingly small linear stress-strain region relative to their breaking strength. If stretched beyond this region, either of two things can happen. Either the material does not fully recover its original dimensions when the stress is removed (plastic deformation), or the material becomes stiffer (e.g., when an elastomer’s folded molecular chains become stretched straight). So when you are given a problem involving stiffness k or Young’s modulus y, there is an implicit assumption of being within the range over which the relations between strain and stress, or force and deformation, remain fairly constant.
