Simple Stress and Strain MCQ with answer and solution

Concept

Modulus of Elasticity of Steel

Formula

E = σ / ε (Young's Modulus = Stress / Strain)

Step-by-step solution

1. Recognize that Young's modulus (E = σ / ε) measures material stiffness and depends on the base iron composition. 2. Note that heat treatment and tensile strength modifications do not alter the fundamental atomic bonds of steel. 3. Conclude that high-tensile steel and mild steel have approximately the same Young's modulus (\~200 GPa), making option B correct.

Explanation

The modulus of elasticity (or Young's modulus) measures the stiffness of a material in the elastic range. Since both high-tensile steel and mild steel share the same base iron structure, their modulus of elasticity remains nearly identical (around 200 GPa) regardless of differences in strength or heat treatment. Therefore, the modulus of elasticity of high-tensile steel is equal to that of mild steel.

Shortcut

Remember: Steel is Steel. Modulus of elasticity (E ≈ 200 GPa) depends on the base material (iron/atomic bonds), not its strength or heat treatment. Therefore, all structural steels—whether mild, high-tensile, or alloy—have equal modulus of elasticity.

Common mistake

Many students confuse high tensile strength with stiffness and incorrectly select Option C (Larger than that of mild steel), assuming that stronger steel must have a higher modulus of elasticity.