Which statement is true?
Try it first: pick an option, then read the explanation.
Correct answer: B. The ability of a material to absorb energy until rupture is known as toughness
Asked in SSC JE 27/01/2018 (Evening)
Detailed Explanation
Several material properties sound similar but mean different things: hardness, toughness, brittleness, resilience.
Why “The ability of a material to absorb energy until rupture is known as toughness” Is Correct
Toughness is the ability to absorb energy (plastic and elastic) up to fracture. On a stress–strain curve it is the total area under the curve; per unit volume it is the modulus of toughness. Tough materials, like mild steel, give warning before failure.
| Property | Meaning |
|---|---|
| Toughness | Energy absorbed up to fracture |
| Resilience | Energy absorbed up to the elastic limit (recoverable) |
| Hardness | Resistance to indentation, scratching or wear |
| Brittleness | Fracture with little deformation or energy |
Why the Other Options Are Wrong
- A. The ability of a material to absorb energy until rupture is known as hardness: Hardness is resistance to indentation or scratching.
- C. The ability of a material to absorb energy until rupture is known as brittleness: Brittleness is the opposite: failure with little energy absorbed.
- D. None of these: Toughness is correct.
Key Point
Toughness → energy to fracture; resilience → energy to elastic limit.
Key Concepts for Students
- Impact tests (Izod, Charpy) measure toughness.
- Modulus of resilience = σ_y²/2E.
- Cast iron is brittle; mild steel is tough.
Practice more: this is question 26 in Stress and Strain MCQs – Part 2. Try the whole set and check every answer instantly.