Final answer:
A force extension graph for a general material such as metal shows the relationship between applied force and deformation, including both elastic and plastic behavior, and ends at the material's point of fracture.
Step-by-step explanation:
Force Extension Graph for a General Material
A force extension graph illustrates the relationship between the applied force and the resulting deformation of a material, typically a metal. Initially, when a load is applied to a metal, it deforms elastically—which means it returns to its original shape once the load is removed. This initial straight portion of the graph obeys Hooke's law, showing that the deformation is directly proportional to the applied force. Beyond the elastic limit, the metal begins to plastically deform, creating permanent changes.
Upon loading, the graph rises linearly (red line) up to point H, the linearity limit. Past this point, the curve moves into a nonlinear region (between H and E) but remains elastic. When the stress reaches the elasticity limit (point E), any further stress causes plastic deformation. If the load is removed after surpassing the elasticity limit (for instance at point P), the graph will decline along a different path (green line), which shows the permanent deformation. Finally, the graph rises sharply just before the material breaks, indicating a large deformation for a small increase in force, characteristic of the point just before fracture.