Clarifying The Actual Definition Of Elasticity. Is Steel Really More Elastic Than Rubber?
Answer : There are two separate concepts here: the Young's modulus, which determines the force needed to stretch the material the elastic limit, aka yield strain, which determines how far the material can be stretched As you say, the term elastic tends to be used in a vague way that conflates these two properties. Generally a high Young's modulus means the material is stiff so I would say steel is stiffer than rubber not more elastic than rubber. Steel also has a much smaller yield strain that rubber because you can't stretch steel far before it starts to deform while rubber can be stretched a long distance. So if you're going to use the vaguely defined term elastic then steel is certainly less elastic than rubber in both meanings. However in a physics or engineering context you would use the precisely defined terms Young's modulus and yield strain instead. Finally: There is another meaning for elastic , which is what Rod has covered in his answ...