Hardness tests are appealing as they are simple cheap nondes

Hardness tests are appealing as they are simple, cheap, non-destructive and provide information about materials\' properties. Based on your understating of hardness measurement which of the following statement is true: Hardness and elastic stiffness are proportionally related and their proportionality constant is universal and the same for all materials Hardness and elastic stiffness are proportionally related but their proportionality constant is not universal and changes from material to material Hardness and elastic stiffness are nonlinearly related None of the above

Solution

option c

Hardness is the resistance to permanent deformation

Stiffness is the relationship between force (or stress) and elastic deformation