| English | Elastic limit |
|---|---|
| Bahasa Melayu | Had kenyal |
| 中文 | 弹性极限 |
Definition
The maximum force or extension beyond which a spring or material no longer returns to its original length.
In exam terms
The elastic limit is the maximum force, or the maximum extension, beyond which a spring or material no longer returns to its original length after the force is removed. Up to this point the behaviour is elastic; past it the material is permanently deformed.
On a force–extension graph the elastic limit marks where reversible stretching ends.
For example, if a spring returns to its original length after loads up to 8.0 N but stays slightly longer after 9.0 N, its elastic limit lies between those two forces. Loading beyond the elastic limit leaves a permanent extension even when the load is taken off.
Don't confuse it with the limit of proportionality
Do not confuse the elastic limit with the limit of proportionality. The limit of proportionality is where extension stops being directly proportional to force (where the straight line first bends); the elastic limit, usually just beyond it, is where the material stops returning to its original length.
Below the limit of proportionality both apply and Hooke's law holds.
In Paper 2 this is usually asked with 'Define…' or 'Mark the elastic limit on the graph'. Describe it as the point beyond which deformation becomes permanent, and give any force in newtons (N).
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)