What is measured as the MINIMUM force per unit of area that causes the material to begin to permanently change its shape?

What is measured as the MAXIMUM force per unit of the area that causes a complete fracture or break in the material?

______ refers to the new undesired bent shape metal takes after an impact of collision.

_____-_____ is the tendency for metal to return to its original shape after deformation.

What happens when plastic deformation has caused the metal to become very hard in the bent area?