A stress–strain curve is a graph plotted between stress (y-axis) and strain (x-axis) for a material when it is subjected to an increasing load.
Initially, stress is directly proportional to strain and the graph is a straight line. This region obeys Hooke’s law.
The point up to which stress is directly proportional to strain.
The maximum stress up to which the material regains its original shape after removal of force.
Beyond this point, the material begins to deform permanently.
The point at which the material breaks.
Q1. Stress–strain curve is plotted between: A) Stress and force B) Stress and strain C) Strain and force D) Load and time Answer: B Q2. The straight-line portion of stress–strain curve obeys: A) Newton’s law B) Hooke’s law C) Law of gravitation D) Pascal’s law Answer: B Q3. The elastic limit is the point: A) Where material breaks B) Up to which Hooke’s law is valid C) Up to which body regains original shape D) Where stress becomes zero Answer: C Q4. Permanent deformation begins after: A) Proportional limit B) Elastic limit C) Breaking point D) Zero strain Answer: B Q5. Yield point indicates: A) Elastic behaviour B) Plastic behaviour begins C) Breaking of material D) Zero stress Answer: B Q6. At breaking point, the material: A) Regains shape B) Stretches elastically C) Deforms plastically D) Breaks Answer: D Q7. Which deformation is reversible? A) Plastic B) Permanent C) Elastic D) Breaking Answer: C Q8. Stress–strain curve is useful to study: A) Electrical properties B) Thermal properties C) Mechanical properties D) Magnetic properties Answer: C
Graph between stress (y-axis) and strain (x-axis).
Stress ∝ strain (Hooke’s law valid).
Maximum stress up to which body regains original shape.
Plastic deformation begins.
Material breaks.
MCQs are frequently asked on identification of points and nature of deformation on stress–strain curve.
