Simple Stress and Strain MCQ with answer and solution

Concept

Ratio of Young's modulus of steel types

Formula

NONE

Step-by-step solution

1. Young's modulus measures the stiffness of a material in the elastic range. 2. High tensile steel and mild steel both have approximately the same Young's modulus of about 2 x 10⁵ N/mm². 3. Thus, the ratio of Young's modulus of high tensile steel to that of mild steel is about 1. Answer: B

Explanation

Young's modulus measures the elastic stiffness of a material, which depends on the atomic bonding of iron regardless of heat treatment or alloy content. Both high tensile steel and mild steel have approximately the same elastic modulus of around 200 GPa. Therefore, the ratio of their Young's moduli is approximately 1.

Why the other options are wrong

A) High tensile steel and mild steel have approximately the same Young's modulus of about 200 GPa. C) Young's modulus depends on the interatomic bonding of steel, which remains constant across different grades. D) Young's modulus does not double for high tensile steel because alloying does not significantly alter elastic stiffness.

Shortcut

Young's modulus is the same (~2x10⁵ MPa) for all steel types, so the ratio is 1.

Common mistake

Assuming high tensile steel has a higher Young's modulus than mild steel due to its higher yield strength.