An object's ability of resist deformation when an external force is applied is called "stiffness." Also, the object’s ability to return to its original shape when the external force is removed is called "elastic deformation." The ratio of external force to elastic deformation is called "Young's modulus."
|Material||Young's modulus (× 1010 N/m2)|
|Polyethylene||0.04 - 0.13|
The lower Young's modulus is, the lower the stiffness is, indicating that the material can be easily deformed. For example, if an object with a low Young's modulus is measured with a micrometer, the object may be deformed if the screw is tightened excessively, which may prevent accurate measurement.