The diagram represents the stress-strain graph of a loaded wire. Which of these statements is correct?
- A. At I, the wire becomes plastic
- B. J is the yield point
- C. L is the elastic limit
- D. At K. the wire breaks
If the above diagram represents the behavior of an elastic material, then:
- Point I is the proportionality limit, it is the point beyond which the material stop obeying Hooke’s law. Also, beyond this point, the material temporarily loses its elasticity and begins to deform.
- Point J is the elastic limit or yield point, it is a point beyond which the material enters into plastic region and permanently loses its elasticity. The material may slowly regain its elasticity if it falls between I and J, but anything beyond J is a region of permanent deformation.
- Point K is the ultimate stress point, it is a point of maximum stress on the material just before breakage.
- Point L is the breaking point, it a point at which the bond closely holding the material together is totally separated and broken.
Now for the right answer to the above question:
- Option A is incorrect. the wire becomes plastic at J and not I.
- Option B is correct. yes, J is the yield point or elastic limit.
- C is incorrect. L is the breaking point and not the elastic limit.
- D is not the correct answer. the wire breaks at L and not K.
You may please note these/this:
- Point J is the yield point, a point beyond which the material becomes plastic.
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/culled from 2019 JAMB-UTME physics question 23/